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11 Cards in this Set

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When does the calcium channel open?
Once smooth muscle L-channels are activated -> activate phospholipase C -> activate phosphokinase C -> phosphorylates the calcium channel, which causes it to open and to calcium to flow into the cell
Where are L-voltage dependent calcium channels located?
smooth muscle, caridac, skeletal muscle
What role does Ca++ play in muscle contraction in cardiac tissue?
Na+ influx -> increase Ca++ influx -> increases intracellular Ca++ -> Ca++ released from sarcoplasmic reticulum -> breaks Troponin C-Actin complex forming Troponin C-Ca++ complex --> the released free actin binds to myosin-P-> muscle contraction
What role does Ca++ play in muscle contraction in vascular smooth muscle tissue?
Intracellular Ca++ binds to Calmodulin -> complex converts myosin light chain kinase (inactive) to myosin light chain kinase-P (active) -> phosphorylates myosin which interacts with free actin -> vascular smooth muscle contraction
Drug effectiveness as a function of channel location 1) cardiac L-channels
Verapamil > diltiazem > nifedipine
Drug effectiveness as a function of channel location
2)Vascular Smooth Muscle
Nifedipine > Verapamil > Diltiazem
What is the structure of Verapamil?
Arylalkylamine
What is the structure of Diltiazem?
Benzothiazepine
What is the structure of Nifedipine?
Dihydropyridine
SAR for the Dihydropyridines
1)Dihydropyridine ring system
2)Phenyl group in position #4 w/ an ortho or meta substituent that is EWG (keep aromatic rings perpindicular)
3)Esters in positions #3 and #5 (if cleaved, therapeutic effect is lost)
What drug/food interaction occurs with CCBs?
Grapefruit juice (increases absorption of CCBs except Diltiazem or amlodipine)