Pharmacology

Question 1

Epinephrine

Answer 1

An Alpha and Beta receptor agonist. Potent vasoconstrictor and cardiac stimulant. The inotropic and chronotropic actions on the heart cause a rise in systolic pressure. But beta 2 activation in skeletal muscles causes those tissues to dilate, lowering diastolic pressure.

Heart
Heart rate Up
Atrial & nodal automaticity Up
Conduction velocity Up
Contractile force Up

Blood Vessels Constrict

Bronchioles Relax
GI tract Slows

Sweat glands Active
Iris Mydriasis

Question 2

Norepinephrine

Answer 2

Alpha 1, 2 and B 1 agonist. Increases peripheral resistance and blood pressure. Resultant baroreflex drops this effect while the inotropic effects on the heart are maintained.

1. Heart
   
   1. Heart rate
   2. Atrial & nodal automaticity
   3. Conduction velocity
   4. Contractile force
2. Blood Vessels
3. Bronchioles
4. GI tract
   1. Motility & tone
5. Sweat glands
6. Iris

Question 3

Isoproterenol

Answer 3

Potent B1 and 2 receptor agonist, with little effect on alpha receptors.

Question 4

Dobutamine

Answer 4

Beta 1 selective agonist. Activates adenylyl cyclase, increasing myocardial contractility. Positive inotropic effect. Used to treat cardiogenic shock, acute heart failure.

Question 5

Clonidine

Answer 5

Alpha 2 agonist, inhibits adenylyl cyclase. Vasoconstricts, but it’s sympatholytic effect lowers blood pressure. Used to treat hypertension.

Question 6

Midodrine

Answer 6

Prodrug, becomes an alpha selective agonist. Used to treat hypotension, but may cause hypertension when the patient is supine.

Question 7

Brimonidin

Answer 7

An Alpha 2 agonist, it inhibits adenylate cyclase reducing cAMP. Used to treat hight intraocular pressure from open angle glaucoma or ocular hypertension.

Question 8

Phenylephrine

Answer 8

Relatively pure alpha1 agonist. Effective mydriatic and decongestant by constricting blood vessels in the nose can raise blood pressure. This has the compensatory effect of increasing vagus pressure, releasing ACh and slowing the Heart.

Question 9

Oxymetazoline

Answer 9

Selective alpha-1 agonist and partial alpha agonist. Used as a topical decongestant in Afrin, Vicks, Sudafed, Visine and Zicam. The alpha 1 action cause vasoconstriction. The topical use of the Alpha 2 agonist allows for post synaptic action that causes constriction rather than dilation.

Question 10

Albuterol

Answer 10

Beta 2 receptor agonist, used to relieve bronchospasms in asthma.

Question 11

Amphetamine

Answer 11

Does not directly affect receptors. Rather it is taken up by Norepinephrine transporters, and blocks the degredation of NE in the synapse. Thus it allows NE to flood out upon release.

Question 12

Ephedrine

Answer 12

A mixed alpha and beta adrenergic agonist, it is used popularly for weight loss. It causes hypertension and bronchodilation.

Question 13

Dopamine

Answer 13

The precursor to norepinephrine. Critical neuro transmitter.

Question 14

Where are Nicotinic receptors found? Where are they not found?

Answer 14

Found on:

• Somatic Nervous system
  
  • On Sekeletal Muscle
• Parasympathetic Nervous system
  
  • On post synaptic neurons of the PSN
  • **NOT on end organs of the PSN - these have Muscarinic instead **
• Sympathetic Nervous system
  
  • On post synaptic nerurons of the SN
  • On Adrenal medullar cells.

Question 15

How does ACh affect the heart?

Answer 15

By binding to Muscarinic M₂ receptors Acetyl Choline causes opeing of K+ channels, hyperpolarizing the cells and slowing conduction of electical signals.

Question 16

Alpha 1 adrenergic receptors. Where are they? What does activating them do?

Answer 16

Activation causes stimulation of Gq - to IP₃ to an increase in intra cellular Ca²⁺ which promotes muscle contractility by acting on tropomyocin.

Systemically this causes smooth muscles in vessles to constict, thereby raising blood pressure. Causes mydriasis in the eyes. GI sphincter contraction. By raising blood pressure there is a vagus response which release ACh and slows the heart.

Question 17

Fenoldopam

Answer 17

A D₁ receptor agonist.

It can treat severe hypertension by increasing renal profusion.

Question 18

Prazosin

Answer 18

An Aplpha1 Blocker,

This will prevent vasoconstriction so when given with something like Norepi you see the effects on heart rate and contractile force, but not on diastolic blood pressure because the peripheral vasculature is still open.

Question 19

Metroprolol

Answer 19

A Beta 1 blocker-

Prevents the actions that increase heart conractility. Therefor when given with something like Epi, you get the vascular effects without any effect on HR. So both systolic and diastolic BP will drop.

Question 20

What are nicotinic receptors, where are they and what do they do?

Answer 20

nAChR_N & nAChR_M receptors,

Found on skeletal muscle, postsynaptic parasympathetic ganglions, post synaptic sympathetic ganglion and the adrenal medulla.

They respond to Nicotine and AcetylCholine - causing them to open and allow Na+ inflow which depolarizes the cell

Question 21

Muscarinic receptors type 1,3 and 5

Answer 21

Respond to ACh, triggering Gq - Phospolipase C - IP3&Dicylglycerol leading to high Ca2+ and Proein Kinase C

Found on Parasympathetic End Organds,