Ca channel blockers and nitrates

Ca CHANEL BLOCKERS
1 Importance
of calcium Chanel activation

in smooth muscle contraction



Ca2t Chanel antagonists
B
A
Benzothiazepines
Dihydropyridines nylalkyamines

Rate
limiting
Mechanism of action
Calcium antagonists block the entry of calcium
through
the calcium Chanel in vascular smooth muscle and

myocardium
Less Ca2T is available for contractile apparatus
Vasodilation
Negative inotropic effects


A Dihydropyridines Nifedipine
Am lodipine
Lercanidipine

, Blocks activation of
L
type Caat channels

Calcium calmodulin
cannot activate

myosin light chain
kinase


B c Benzothiazi pines Diltiazem
Phenylalky amines Verapamil
Blocks activation of
L
type Coit Channel

Calcium troponin
cannot activate actin

myosin myo filaments



NB Both intracellular calcium to relax either
smooth muscle vasodilation or cardiac muscle cell