Vasodilators/Vasoconstricters Flashcards
why does increasing K+ channel opening relax vascular smooth muscle?
the harder it is to depolarize the membrane enough to open Ca2+ gated channels
name the 3 K+ channel openers
minoxidil, diazoxide, adenosine
side effect of minoxidil
hypertrichosis (excess hair)
diazoxide administration and uses
IV for drug-resistant HTN
inhibits release of insulin
used for hypoglycemia secondary to hyperinsulinemia
what does adenosine do to the membrane?
hyperpolarization and relaxation
what does adenosine bind
A1 a GPCR
what is adenosine used for
coronary stress test
supraventricular arrhythmias
what does adenosine activate that kicks K+ out of the cell?
GIRK
what happens in vascular endothelium
calcium-calmodulin activates eNOS which helps convert arginine to NO
where is eNOS found
endothelium
where is guanylate cyclase found
vascular smooth muscle
what does NO do in smooth muscle
binds heme group on guanylate cyclase and stimulates cGMP and activation of protein kinase g
how does protein kinase G relax smooth muscle? (4 ways)
inhibits Cav 1.2
stimulation of Ca/K channels (BKca)
decreased MLC phosphorylation
enhanced Ca uptake in ER (phospholambam)
organic nitrates MOA
non selective vasodilators
breakdown to NO (bioactivation)
do organic nitrates require functional endothelium
no
what are nitrates used for?
sublingually for angina
oral for prolonged prophylaxis
what happens with continuous admin of nitrates”?
tolerance
asian population has an allele that decreases efficacy of what?
glycerol trinitrate
lys 504 allele
sodium nitroprusside dilates what
veins and arterioles
what is sodium nitroprusside metabolized to and where?
in erythrocytes to NO and CN which limits duration of treatment (toxic)