Dihydropyridines membrane concentration

Q13 Calcium channel blockers decrease the opening of L-type calcium channels in the plasma membrane of vascular smooth muscle cells, and so reduce intracellular calcium concentration and contractile activity. The blood vessels therefore dilate. Calcium channel blockers act mainly on the arterial side of the circulation, and the dihydropyridines, such as nifedipine, are useful coronary arteriolar dilator agents. These agents are usually the treatment of choice for Prinzmetal angina. 

Nitrendipine is a 1,4-dihydropyridine derivative calcium-entry blocker structurally similar to nifedipine. It is further classified as a type II calcium antagonist because, at usual doses and concentrations, it is devoid of electrophysiologic effects, but is a potent peripheral vasodilator. Relaxation of peripheral vascular smooth muscle occurs as a result of inhibition of calcium influx across cellular membranes. 

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