pharmacology 7 - autonomic Flashcards
examples of ganglionic blockers for the Nm receptors of the PNS? Nm antagonists cause?
trimetaphan - hypotension and loss of CV responses. controlled hypotension during anaestesia. not used in vet med!! antagonists cause muscle relaxation!!
Pns drugs. which work on the nicotinic not often used why? which ones are used more though?
also effect the SNS. the Nm receptor is used more as it is not common with the SNS but is part of the afferent somatic NS.
drugs used in the SNS? act where?
they act at the adrenergic receptors. postganglionic.
alpha and beta 1 &2. varied selectivity.
what are endogenous ligands of the SNS?
epinephrine, NA, dopamine. postsynaptically
pre-synaptically - ACH at nicotinic.
if we use an antagonist at the Nm receptor to relax mm……….then want to reverse it? what do we use? but….this cause increased ACH everywhere resulting in? what can we then use to reverse this?
reverse - ACHEI. (increase ACH).
causes increased HR, and lowered gi tract. use atropine then (muscarinic antagonist to reverse this!!)
give an example of a non-selective agonist in the SNS? what does it do? side effect?
adrenaline!!! increases HR and force and speed, causes vasoconstriction used when cardiac arrest and anaphylaxis. metabolised by MAO and COMT. same as NA is. (MAO = reuptake.) give intratracheal, i/v or into heart. may induse tachycardia or arrythmia.
give an example of a non-selective B agonist? metabolised by what ? why not MAO?
isoprenaline. causes positive effects on heart.
can induce arrythmias and mycardial necrosis.
metabolised by COMT in the liver (not MAO as it is not endogenous!)
give an example of a non-selective alpha agonist? used to? which nervous system?
phenylpropanolamine!! treats urinary incontinence and the bitch. (imporves sphincter tone!!) given orally. nasal decongestant.
adverse effects can be agression /excitement.
causes release of NA. must make sure that the bladder can empty.
what does dopamine do as a drug? what receptors? acts on which organ mainly?
receptors d1-d5.
d1 is in renal c=vasculature. it promotes renal blood flow using increased CAMP - vasodilation.
increases perfusion and filtration
at higher doses may induce a vasocinstraiction at the alpha 1 receptor.
give an example of B1 AGONIST (SELECTIVE) eg? given how? used when?
has heart affects 9increased)
dobutamine - used in equine anaesthesia to maintain mean arterial pressure (reduce myopathy)
used in acute cardiac crisis. administered by i/v infusion due to a low half life. and rapidly metabolised.
give an example of a b2 agonist? what do they do?muscle mass? how?
clenbuterol: treat copd in horses as causes bronchdilation. orally or i/v. cause vasodilation and tachycardia. (high CAMP in vasculature so dilates) used as repartioning agent - distribution of fat vs muscle!
terbutaline: bronchdilation, aid cardiac affects, gien orally.
another b2 agnist drug? isoxuprine used to do what? what is tocolytic? how would you reverse the effect? good for c-section etc why?
isoxuprine: treats navicular disease in horses. vasodilation!.
tocolytic drug - dont stop even when stop drug itself.
good for a c-section or embryotomy to stop contractions. and delays partuition. reverse effect with oxytocin.
give an example of an alpha 1 agonist? what does it do?
phenylephrine: induces vasoconstrition. increases force of contraction.
induces mydriasis.
give an exapmle of a alpha 2 agonist drug? what does it do?
sedative effects. xylazine.
clenidine - diagnose growth hormone deficiency (stim ghrf)
what would an alpha 1 antagonist do? eg?
causes vasodilation. phenoxybenzamine - irreversible
treats laminitis
treat urinary retention! - sphincter relax!
induce hypotension
prazosin - urinary tract treatment - contracts detrusor to make you pee. - makes sure shincter releax to stop rupture!!!
