Lecture 8 Ca channel blockers Flashcards
what determines the direction of flow in an ion channel?
concentration and electrical gradient
excitable cells have a ____ inward potential across the membrane due to the selective permeability of the resting membrane to ____
negative;
K+
K is high ____ and low ____ the cell.
Na is high ____ and low ____ the cell.
Calcium is very low ____ and high ____ the cell
inside, outside;
outside, inside;
inside, outside
2 main components of voltage gated channels:
selectivity filter, gate
___ type Calcium channels are located on cardiac, smooth, and skeletal muscle
L
Voltage gated calcium channels type 2 are found where? what do they do
neurons, trigger NT release
The voltage gated calcium channel type _ . ___ is what is targeted by calcium channel blockers
1.2 (probably not very high yield tbh)
Calcium Channel blockers (CCBs) that block channels in vascular smooth muscle cause _____. CCBs that block channels in cardiac muscle are _____
vasodilation; anti-arrhythmic
vascular smooth muscle: _____ causes Calcium influx via ____ channels. this induces release of calcium from intracellular stores via _____ receptor located in the ____
depolarization, CaV1.2 (ie L-type);
ryanodine receptor 2; Sarcoplasmic reticulum
extracellular calcium is required for contraction of what kind(s) of muscle? what kind(s) of muscle is extracellular Ca not required in?
required in cardiac/smooth muscle;
not required in skeletal muscle
The increase in intracellular Calcium causes it to bind ___. This activates _____, which acts upon myosin light chain. ______ of myosin light chain causes it to complex with ____, causing contraction to ensue.
calmodulin, myosin light chain kinase;
phosphorylation, actin
Cardiac muscle: Calcium ions released from the sarcoplasmic reticulum bind to ____. Binding of this causes displacement of ____, allowing ____ to bind ____ and contraction
troponin C;
tropomyosin; myosin+Actin
what are the three chemical classes of CCBS
dihydroppyridines, phenylalkylamines, benzothiazepines
all dihydropyridines end in ____
“-dipine” ie nifedipine, isradipine, felodipine etc
Dihydroppyridines bind where on the receptor?
NOT the binding site; allosteric modulators
______ is a dihydropyridine that has a very short half life. it is given in acute settings via IV ie HTN emergency
clevidipine
what is clevidipine formulated with? (ie allergy risk)
soy, egg
where do dihydropyridines (DHPs) act? they cause what?
vascular muscle, esp coronary arteries; vasodilation
NOT ANTI-ARRHYTHMIC
Binding of DHPs is ____ dependent ! Why is this important?
voltage; smooth muscle of vasculature has elevated resting membrane potential = bind more
DHP’s bind to _____ channels and prevent ____. This is caused ____ block
closed, opening;
TONIC
DHPs preferentially vasodilate ____. This causes decreased _____
arterioles, afterload
_____ is the DHP with the poorest vasodilatory action
nifedipine
_____ exhibits selectivity for cerebral arteries. Use it in ______ ____ to prevent neuropathy
nimodipine, subarachnoid hemorrhage
all DHPs cause ____ ____ secondary to vasodilation, except for ____, which has slow action
reflex tachy;
amlodipine
