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Introduction To Pharmacology I > Autonomic Nervous System: Adrenergic Agonists > Flashcards

Autonomic Nervous System: Adrenergic Agonists Flashcards

1
Q

What is the classifications of drugs that mimic the pharmacological and physiologic actions of endogenous catecholamines? What are their effects mediated by?

A

Drugs that mimic the pharmacological and physiological actions of the endogenous cathecolamines are classified as **sympathomimetic drugs. **Their effects are mediated by activation of adrenergic receptors located on effector cells and tissues

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2
Q

What mediates NE release from nerve terminals? When released what does NE bind to?

A
  • Sympathetic nerve activity mediates NE release from nerve terminals
  • Released NE binds to and activates adrenergic receptors located on postsynaptic effector
    tissues and at presynaptic sites
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3
Q

What are the classifications of adrenergic agonists?

A

The adrenergic agonist are classified as: Direct-acting, indirect-acting, and mixed-acting

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4
Q

What does the capacity of the sympathomimetic drugs to produce physiological responses depend on?

A

Similarity of the chemical structure of sympathomimetic drugs to that of NE and EPI

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5
Q

What are direct acting adrenergic agonists?

A

Neurotransmitter and drug bind directly to and activate adrenergic receptor

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6
Q

What are indirect acting adrenergic agonists?

A

They mediate physiological response that involves increasing the synaptic levels of endogenous catecholamines

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7
Q

What are mixed acting adrenergic agonists?

A

Some drugs demostrate the capability to directly activate adrenergic receptors and also to increase the release of NE from adrenergic nerve terminals

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8
Q

Many adrenergic receptor agonists demostrate a level of ________ for specific _________.

A

Many adrenergic receptor agonists demostrate a level of selectivity for specific adrenergic receptors

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9
Q

True or False: An endogenous catecholamine or sympathomimetic drug only has a specificity for one type of adrenergic receptor.

A

An individual endogenous cathecolamine or sympathomimetic drug may exihibit a higher affinity
or selectivity for one or more subtypes of adrenergic receptors

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10
Q

What are pharmacologic interactions between agonists and adrenergic receptors influenced by?

A
  • The tissue distribution of adrenergic receptors
  • The number of adrenergic receptors expressed at specific sites * Interaractions between the sympathetic and parasympathetic nervous systems at target sites
  • Pathophysiological and disease states
  • The background level of sympathetic nerve activity
  • Levels of endogenous catecholamines and /or sympathomimetic drugs
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11
Q

What is desensitization?

A

Prolonged exposure of adrenergic receptors to specific agonist reduces the responsiveness of these receptors, producing a progressive attenuation in the tissue‘s capacity to facilitate physiological responses

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12
Q

What are the 3 proposed mechanisms used to describe desensitization?

A
  1. Sequestration of receptors so that they are unavailable for interaction with the ligand
  2. Down-regulation, that is, a disappearence of the receptors by destruction or by decreased
    synthesis
  3. An inability to couple to G-protein, because the receptor has been phosphorylated on the
    cytoplasmic side
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13
Q
A
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14
Q
A
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15
Q

What is the physiologic responses seen with stimulation of A1 receptor for the following tissues:
- Most vascular smooth muscle (innervated)
- Pupillary dilator muscle
- Urethral smooth muscle
- Splenic capsule

A

Most vascular smooth muscle (innervated) - Contraction
Pupillary dilator muscle- contraction ( pupil dialation)
Urethral smooth muscle- Contraction
Splenic capsule- contraction

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16
Q

What is the physiologic responses seen with stimulation of A2 receptor for the following tissues:
- Platelets
- Adrenergic and cholinergic nerve terminals
- Selected vascular smooth muscle

A

Platelets- Aggregation
Adrenergic and cholinergic nerve terminals - Inhibits transmitter release
Selected vascular smooth muscle- Contraction

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17
Q

What is the physiologic responses seen with stimulation of B1 receptor for the following tissues:

A
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18
Q

What is the physiologic responses seen with stimulation of B2 receptor for the following tissues:

A
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19
Q

What is the physiologic responses seen with stimulation of B3 receptor for the following tissues:

A
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20
Q

What is the physiologic responses seen with stimulation of D1 receptor for the following tissues:

A
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21
Q

What is the physiologic responses seen with stimulation of D2 receptor for the following tissues:

A
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22
Q
A
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23
Q

What would be the receptor you would like to influence in this case? What should this receptor do?

A
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24
Q

What is responsible for maintaining baseline airway tone? Activation of muscurinic receptor will cause what effect on bronchoal smooth muscle?

A

PSNS is responsible for maintaining baseline airway tone and activation of bronchial muscarinic receptors produces contraction of bronchial smooth muscle

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25
Q

What are the selective B2 adrenergic receptor agonists used for respiratory function?

A

Terbutaline
Albuterol
Clenbuterol

26
Q

What is terbutaline? How is it administered? What effect does it have on cardiac B1 receptors? A adrenergic receptors?

A
27
Q

What is albuterol? What is it used for? How can it be administered? What is another use of aerosolized albuterol for anesthesized horses?

A

Selective B-2 agonist

28
Q

What animal is clenbuterol contraindicated for?

A

It is contraindicated in food producing animals

29
Q

What is clenbuterol? What is it used for? What is its method of administration?

A
30
Q

What are potential causes of hypotension for this patient? Why?

A

The use of isofourane can cause hypotension even at subanesthetic doses.

31
Q

What is the main mechanism for hypotension with isoflourane?

A

It causes a reduction in peripheral vascular resistance (main mechanism for the decrease
in blood pressure

32
Q

What occurs with higher doses of isoflourane/

A
  • Higher doses of isoflurane reduces cardiac output with depressant effets on myocardial contractility
33
Q

What are the drugs typically used for treatment of hypotension under the described clinical situation ( lab under anesthesia)?

A

Dopamine, ephedrine, and dobutamine

34
Q

What is Dopamine? What does iv administration of low dose dopamine cause? What about moderate infusion rates? What about higher rates?

A

Dont need to know doses

35
Q

What is ephedrine? What can you see with low doses of ephedrine? What may low dose ephedrine activate? What about higher doses?

A
36
Q

What is dobutamine? What is it mainly selective for? What does administration cause? What is it useful in treating? Why is it less effective treatment for isoflourane induced hypotension?

A
37
Q

What is NE, Epinephrine and phenylephrine?

A

They are additional sympathomimetics that can increase arterial blood pressure

38
Q

What drug can reverse marked hypotension and cardiac irregularities from anaphylactic shock? Why?

A

EPI is a potent cardiac stimulant and vasoconstrictive agent. Epinephrine

39
Q

What must you do when giving a CRI of epinephrine?

A

There is interpatient variability, so monitor arterial blood pressure carefully

40
Q

What is epinephrines role in the renal system? What is the consequence of this?

A

EPI is a potent renal vasoconstrictor (It can result in decreases in renal blood flow at higher doses)
( Chances of renal infarct, ischemia, AKI, ect)

41
Q

What is another transmitter used in clinically hypotensive situations? What is its response on the arteries and veins? What about renal system?

A
  • NE is used clinically in hypotensive situations. NE induces marked constriction of arteries and veins
  • NE is a potent constrictor of renal vascular beds
42
Q

When would you use phenylephrine in a hypotensive patient?

A

When you need to produce peripheral vasoconstriction in situations where cardiac output is adequate.

43
Q

Drugs that are selective ___________ or have potent α-adrenergic activity and minimal __________ adrenergic effects can cause significant vasoconstriction.

A

Drugs that are selective α-adrenergic agonists or have potent α-adrenergic activity and minimal β
2 -adrenergic effects can cause significant vasoconstriction

44
Q

What is the outcome if you add epinephrine to local anesthetics?

A

The addition of EPI to local anesthetics to delay removal of the anesthetic from site of injection

45
Q

Why does Phenylephrine cause a reduction in splenic size?

A
  • α1-adrenergic receptors are expressed on the smooth muscle of the splenic capsule. The SNS
    activation to this target produces smooth muscle contraction
  • Phenylephrine, an α 1 -adrenergic selective receptor agonist causes splenic muscle contraction,
    discharges RBC into the circulation and reduces the size of the spleen
46
Q

Why may we give phenylephrine to a horse who has nephrosplenic entrapment?

A

Phenylephrine administration reduces splenic area and thickness making room for the colon to dislodge from the nephrosplenic space

47
Q

What medication is used to cause mydraisis in dogs prior to cataract surgery?

A

The selective α 1 -adrenergic receptor agonist phenylephrine, is used in pupillary dilation
(mydriasis) protocols for dogs prior to cataract surgery
α 1 -adrenergic receptors are expressed on the radial dilator muscle of the iris (iris dilator muscle) and on conjunctival blood vessels

48
Q

What is the effect of topical application of phenylephrine topically on the eye?

A

Following topical application, phenylephrine produces contraction of the smooth muscle of the
conjunctival blood vessels and of the iris dilator muscle, causing blanching of the conjunctival
vasculature and pupillary dilation

49
Q

What does horners syndrome cause?

A
  • Miosis (constriction of the affected pupil)
  • Drooping of the upper eyelid (ptosis)
  • An inward sinking of the eyeball (enophthalmos)
  • Partial protrusion of the third eyelid (nictitating membrane)
50
Q

What occurs when you apply a dilute solution of phenylephrine to both eyes in an animal with horners syndrome?

A

After application of a dilute solution of phenylephrine to both eyes:
* In unilateral postganglionic Horner‘s syndrome, the affected pupil should dilate
within 20 minutes
* Other clinical signs will improve or completely resolve

51
Q

What is horners syndrome?

A

oculosympathetic palsy

52
Q

What is apraclonidine and brimonidine? What is their effect on aqueous humpr production? What about intraocular pressure? Is it recommended in veterinary patients?

A
53
Q

What receptors are expressed on the ureters?

A

B2 receptors

54
Q

What receptors are expressed on the detrusor muscle of the bladder body?

A

B2 and B3 receptors

55
Q

What receptors are expressed at the bladder base?

A

a-1 receptors

56
Q

What receptors are expressed at the internal urethral sphincter?

A

a1 receptors

57
Q

Stimulating the sympathetic nerves innervating the urinary tract will cause?

A
  • Smooth muscle relaxation of the bladder body (via β 2-receptors)
  • Smooth muscle contraction at the bladder base (via α 1 –receptors)
  • Internal urethral sphincter contraction by activation of α
    1 –receptors
58
Q

What is the most common acquired urinary incontinence of female dogs and cats?

A

Urethral sphincter incompetence

59
Q

What medication can be given to a dog or cat with Urethral sphincter incompetence in order to increase urethral pressure?

A

A single daily dose of phenylpropanolamine (PROIN) results in an increase in urethral pressure values and improved urinary incontinence

60
Q

What B adrenergic agonist is used in food production as a growth promoter?

A

Ractopamine

61
Q

What is Ractopamine? What animals is it used in? What is its effect in these animals?

A

Introduction To Pharmacology I (26 decks)

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