9.0 Question Bank

Question 1

<div><div><div><div>Statins are used to treat atherosclerosis. Which of the following is the major molecular target of statins in the liver?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. 3-hydroxy-3-methylglutaryl-coenzyme A (HMG CoA) reductase</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Low density lipoprotein (LDL) receptor</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. SRE-binding protein (SREBP)</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. SREBP cleavage activating protein (SCAP)</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Sterol response element (SRE)</div></div></div></div></div></div></div>

Answer 1

A. 3-hydroxy-3-methylglutaryl-coenzyme A (HMG CoA) reductase

Question 2

<div><div><div><div>Hypertension is a major risk factor for myocardial infarction.Which of the following factors is beneficial strategy to treat hypertension?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Increase cardiac afterload</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Increase cardiac preload</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Increase renal Na⁺ excretion</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Increase renal water reabsorption</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Increase vascular resistance</div></div></div></div></div></div></div>

Answer 2

C. Increase renal Na⁺excretion

Question 3

<div><div><div><div>A new antidysrhythmic agent, CV307, has been developed. Its mechanism of action has been compared to other available antidysrhythmic agents.CV307 rapidly blocks voltage-gated Na+ channels in a use-dependent manner and preferentially binds to the inactive state of voltage-gated Na+ channels. Which current antidysrhythmic agent is most similar in action to CV307?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Amiodarone</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Atenolol</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Flecainide</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Lidocaine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Quinidine</div></div></div></div></div></div></div>

Answer 3

D. Lidocaine

Question 4

<div><div><div><div>Which of the following is a beneficial strategy in the treatment of angina pectoris?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Increasing cardiac afterload</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Increasing excretion of Na+</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. A positive chronotropic effect</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Inhibition of the late inward Na+ current</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Inhibition of T-type Ca2+ channels</div></div></div></div></div></div></div>

Answer 4

D. Inhibition of the late inward Na+ current

Question 5

<div><div><div><div>Pain in angina is caused by myocardial ischaemia. Which of the following factors is least likely to predispose those with stable angina to pain?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Positive chronotropy</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Increasing circulating volume</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Reduced time in diastole</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Positive inotropy</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Reduced cardiac efficiency</div></div></div></div></div></div></div>

Answer 5

D. Positive inotropy

Question 6

<div><div><div><div>Hypercholesterolaemia is well known to contribute to cardiovascular disease. Which of the following mechanisms may be useful in preventing the generation of atherosclerotic plaques?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Transfer of cholesterol from peripheral tissues to the blood in the form of HDL</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Antagonism of peroxisome proliferator-activated receptors (PPARs)</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Agonism of HMG CoA reductase to increase the hepatic concentration of mevalonate</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Antagonising lipoprotein lipase (releasing triglycerides from lipoproteins)</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Increasing uptake of sterols from the gut</div></div></div></div></div></div></div>

Answer 6

D. Antagonising lipoprotein lipase (releasing triglycerides from lipoproteins)

Question 7

<div><div><div><div>Which of the following conditions is not a cause of secondary (not essential) hypertension?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Phaeochromocytoma</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Liddle's syndrome</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Kidney failure</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Myasthenia gravis</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Hyperaldosteronism (Conn's Syndrome)</div></div></div></div></div></div></div>

Answer 7

D. Myasthenia gravis

Question 8

<div><div><div><div>Regarding drugs that can act on steroid receptors</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Fludrocortisone can be used to treat postural hypotension</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Spironolactone is an agonist at the mineralocorticoid receptor</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Tamoxifen is an anti-cancer drug that agonises oestrogen at the oestrogen receptor</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Norethisterone is a contraceptive that antagonises the progesterone receptor</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Hydrocortisone can cause postural hypotension</div></div></div></div></div></div></div>

Answer 8

A. Fludrocortisone can be used to treat postural hypotension

Question 9

<div><div><div><div>In a radioligand binding assay, the alpha 1 adrenoceptor antagonist prazosin was used to displace the specific binding of 100 nM [³H]phenylephrine.The affinity constants for prazosin and [3H]phenylephrine were 1.1x10⁸ M^-1 and 0.5x10⁸ M^-1 respectively. What is the IC₅₀ for prazosin displacement of [3H]phenylephrine?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. 54 pM</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. 0.54 nM</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. 54 nM</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. 54 μM</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. 0.54 mM</div></div></div></div></div></div></div>

Answer 9

C. 54 nM

Question 10

<div><div><div><div>Pertussis toxin is a useful substance for studying G protein-coupled receptor (GPCR) signalling.Which of the following best describes the action of pertussis toxin?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. ADP-ribosylation of α_i</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. ADP-ribosylation of α_q</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. ADP-ribosylation of α_s</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. ADP-ribosylation of β</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E.ADP-ribosylation of γ</div></div></div></div></div></div></div>

Answer 10

A. ADP-ribosylation of α_i

Question 11

<div><div><div><div>Receptor desensitisation commonly occurs following prolonged exposure to an agonist. Which of the following best describes a mechanism of homologous desensitisation in β adrenoceptors?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. β adrenoceptor kinase (βARK) phosphorylates sites at the N-terminal</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Phosphorylation enhances affinity for β-arrestin</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Phosphorylation enhances G protein coupling</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Phosphorylation occurs at low agonist concentrations</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Protein kinase A (PKA) phosphorylates sites at the C-terminal</div></div></div></div></div></div></div>

Answer 11

B. Phosphorylation enhances affinity for β-arrestin

Question 12

<div><div><div><div>Drug-receptor interactions can be described with regards to both affinity and efficacy. Which of the following best describes what is meant by effective concentration 50 (EC₅₀)?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. The concentration of a drug that displaces 50% of agonist binding</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. The concentration of a drug that inhibits 50% of a full agonist response</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. The concentration of a drug that occupies 50% of the receptors</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. The concentration of a drug that produces 50% of the maximal response</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. The concentration of a drug that produces 50% of the maximum specific binding</div></div></div></div></div></div></div>

Answer 12

D. The concentration of a drug that produces 50% of the maximal response

Question 13

<div><div><div><div>Local anaesthetics have a variety of clinical uses. Under experimental circumstances how can quaternary local anaesthetics most effectively produce anaesthesia?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Application of a depolarising pre-pulse</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Intracellular application</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Lowering of the extracellular solution pH</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Lowering of the stimulation rate</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Raising of the intracellular solution pH</div></div></div></div></div></div></div>

Answer 13

B. Intracellular application

Question 14

<div><div><div><div>Nicotinic acetylcholine receptors (nAChR) mediate fast neurotransmission. Which of the following best describes the structure of nAChRs?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Dimeric ion channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Hexameric ion channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Pentameric ion channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Tetrameric ion channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Trimeric ion channels</div></div></div></div></div></div></div>

Answer 14

C. Pentameric ion channels

Question 15

<div><div><div><div>Adrenoceptors mediate the biological effects of the catecholamines. Which of the following best describes the signalling events associated with stimulation of adrenoceptors?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. α₁-adrenoceptor stimulation leads to activation of adenylyl cyclases</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. α₂-adrenoceptor stimulation leads to inhibition of phospholipase C</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. β₁-adrenoceptor stimulation leads to production of cAMP</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. β₂-adrenoceptor stimulation reduces the level of cAMP</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. β₃-adrenoceptor stimulation leads to increase in cytosolic free Ca²⁺ concentration</div></div></div></div></div></div></div>

Answer 15

C. β₁-adrenoceptor stimulation leads to production of cAMP

Question 16

<div><div><div><div>Reduced salivation was required for a patient in preparation for an oral surgical procedure. Which of the following strategies will be the best in reducing salivation?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Activation of muscarinic receptors in the salivary glands</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Activation of nicotinic receptors in the salivary glands</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Blockade of adrenoceptors in the salivary glands</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Blockade of muscarinic receptors in the salivary glands</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Blockade of nicotinic receptors in the salivary glands</div></div></div></div></div></div></div>

Answer 16

D. Blockade of muscarinic receptors in the salivary glands

Question 17

<div><div><div><div>Atropa belladonna is a plant that is enriched in atropine. Which of the following drugs will be the most suitable in treating poisoning with belladonna?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Hemicholinium</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Ipratropium</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Malathion</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Physostigmine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Propranolol</div></div></div></div></div></div></div>

Answer 17

D. Physostigmine

Question 18

<div><div><div><div>Sarin is an organophosphate, which is also known as a nerve gas. Which of the following could best serve as an antidote to sarin poisoning?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Atropine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Carbachol</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Nicotine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Physostigmine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Pilocarpine</div></div></div></div></div></div></div>

Answer 18

A. Atropine

Question 19

<div><div><div><div>A blood vessel ring is mounted in an organ bath and its contraction is monitored. Noradrenaline was found to trigger contraction.Which drug is most likely to block this effect</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Phenylephrine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Physostigmine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Pirenzipine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Prazosin</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Propranolol</div></div></div></div></div></div></div>

Answer 19

D. Prazosin

Question 20

<div><div><div><div>Noradrenaline is synthesised from tyrosine.Which of the following drugs will most effectively block the rate-limiting step in this pathway?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. α-methyldopa</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. α-methyltyrosine</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Carbidopa</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Disulfiram</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Tyramine</div></div></div></div></div></div></div>

Answer 20

B. α-methyltyrosine

Question 21

<div><div><div><div>Reperfusion of a vessel following thrombosis can be improved by clot lysis. Which statement best describes the action of streptokinase to improve clot lysis?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. It inhibits factor XIIIa</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. It activates plasminogen</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. It inhibits platelet P2Y12</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. It activates protein C</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. It inhibits thrombin activity</div></div></div></div></div></div></div>

Answer 21

B. It activates plasminogen

Question 22

<div><div><div><div>Excessive platelet activation can result in thrombosis.Which statement best describes the action of clopidogrel as an anti-thrombotic?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. It inhibits COX-1</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. It inhibits GPIIb/IIIa</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. It inhibits P2Y₁₂</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. It inhibits PAR-1</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. It inhibits thrombin</div></div></div></div></div></div></div>

Answer 22

C. It inhibits P2Y₁₂

Question 23

<div><div><div><div>Cardiac glycosides have a positive inotropic effect. Which of the following best describes the mechanism of action of these drugs?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. They inhibit delayed rectifying K⁺ channel K_v11.1</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. They inhibit phosphodiesterase III</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. They inhibit the Na⁺/K⁺-ATPase</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. They inhibit the plasma membrane Ca²⁺ ATPase (PMCA)</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. They inhibit the sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA)</div></div></div></div></div></div></div>

Answer 23

C. They inhibit the Na⁺/K⁺-ATPase

Question 24

<div><div><div><div>Thiazide diuretics may be used to reduce extracellular fluid volume. What is their principal mechanism of action</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Inhibition of aldosterone receptors</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Inhibition of carbonic anhydrase</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Inhibition of epithelial Na⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Inhibition of Na⁺/Cl^- cotransporter</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Inhibition of Na⁺/2Cl^-/K⁺ cotransporter</div></div></div></div></div></div></div>

Answer 24

D. Inhibition of Na⁺/Cl^-cotransporter

Question 25

<div><div><div><div>Hypokalaemia is a problematic side effect of loop diuretics. What is the main reason this occurs?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Loop diuretics activate apical K⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Loop diuretics activate basolateral Na⁺/K⁺ ATPase activity</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Loop diuretics inhibit K⁺ reabsorption in the loop of Henle</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Loop diuretics increase Na⁺ load in the distal tubule</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Loop diuretics inhibit the basolateral K⁺/Cl^- exchanger in the distal tubule</div></div></div></div></div></div></div>

Answer 25

D. Loop diuretics increase Na⁺load in the distal tubule

Question 26

<div><div><div><div>Cardiac action potentials consist of inward and outward currents.Which of the following channels is chiefly responsible for a sustained outward current in ventricular myocytes during the action potential?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Delayed rectifier K⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Inward rectifier K⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. L-type Ca²⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Na⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. T-type Ca²⁺ channels</div></div></div></div></div></div></div>

Answer 26

A. Delayed rectifier K⁺channels

Question 27

<div><div><div><div>Inodilators increase the force of cardiac contraction and cause vasodilatation. What is the principle mechanism by which they have these two effects?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Activation of adenylyl cyclase</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Activation of β-adrenoceptors</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Activation of K⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. Inhibition of the Na⁺/K⁺ ATPase</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Inhibition of phosphodiesterases</div></div></div></div></div></div></div>

Answer 27

E. Inhibition of phosphodiesterases

Question 28

<div><div><div><div>Ion channels play an essential role in the cardiac action potential. The effects of a new ion channel blocker on the ventricular action potential are investigated. Rapid depolarisation is blocked, but a slower depolarisation and plateau phase are seen.Which is the most likely target of this blocker?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Delayed rectifier K⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. L-type voltage-gated Ca²⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Na⁺/K⁺ ATPase</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. T-type voltage-gated Ca²⁺ channels</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Voltage-gated Na⁺ channels</div></div></div></div></div></div></div>

Answer 28

E. Voltage-gated Na⁺channels

Question 29

<div><div><div><div>Spirolonolactone is a diuretic with a relatively slow rate of onset. What best accounts for this slow rate?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. Its effects depend on increasing protein synthesis</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. Its effects depend on protein turnover</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. Its effects depend on the rate of aldosterone synthesis</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. It is metabolised in the liver</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. Its target tissue is poorly perfused</div></div></div></div></div></div></div>

Answer 29

B. Its effects depend on protein turnover

Question 30

<div><div><div><div>Reperfusion of a vessel following thrombosis is necessary for the affected tissue to recover. Which statement best describes the action of plasmin in reperfusion?</div></div></div></div>

<div><div><div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>A. It activates protein C</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>B. It degrades fibrin</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>C. It inhibits platelet aggregation</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>D. It inhibits thrombin generation</div></div></div></div><div><div><div><div><div></div><div></div><div><div><div></div></div></div></div></div><div><div>E. It inhibits thrombin activity</div></div></div></div></div></div></div>

Answer 30

B. It degrades fibrin