Binding of the calcium channel blocker nitrendipine to its receptor in purified sarcolemma from canine cardiac ventricle.

High affinity binding of the 1,4-dihydropyridine calcium channel blocker [3H]nitrendipine was found in cardiac sarcolemma but not cardiac sarcoplasmic reticulum or mitochondria. Sarcolemmal binding of [3H]nitrendipine was saturable and reversible, with a maximum (Bmax) of approximately 1 pmol/mg protein and a Kd of approximately 0.14 nM. Displacement of sarcolemma-bound [3H]nitrendipine by other nifedipine analogs was stereospecific. The Kd for nitrendipine binding was approximately three orders of magnitude lower than the IC50 for the negative inotropic effect of this drug on isolated cat myocardium.