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11 Cards in this Set
- Front
- Back
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When does the calcium channel open?
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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
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Where are L-voltage dependent calcium channels located?
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smooth muscle, caridac, skeletal muscle
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What role does Ca++ play in muscle contraction in cardiac tissue?
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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
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What role does Ca++ play in muscle contraction in vascular smooth muscle tissue?
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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
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Drug effectiveness as a function of channel location 1) cardiac L-channels
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Verapamil > diltiazem > nifedipine
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Drug effectiveness as a function of channel location
2)Vascular Smooth Muscle |
Nifedipine > Verapamil > Diltiazem
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What is the structure of Verapamil?
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Arylalkylamine
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What is the structure of Diltiazem?
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Benzothiazepine
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What is the structure of Nifedipine?
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Dihydropyridine
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SAR for the Dihydropyridines
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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) |
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What drug/food interaction occurs with CCBs?
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Grapefruit juice (increases absorption of CCBs except Diltiazem or amlodipine)
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