RT Journal Article SR Electronic T1 Interaction of SR 33557 with skeletal muscle calcium channel blocker receptors in the baboon: characterization of its binding sites. JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 595 OP 602 VO 257 IS 2 A1 Sol-Rolland, J A1 Joseph, M A1 Rinaldi-Carmona, M YR 1991 UL http://jpet.aspetjournals.org/content/257/2/595.abstract AB A procedure for the isolation of primate skeletal microsomal membranes was initiated. Membranes exhibited specific enzymatic markers such as 5'-nucleotidase, Ca++,Mg(++)-adenosine triphosphatase and an ATP-dependent calcium uptake. Baboon skeletal microsomes bound specifically with high-affinity potent Ca++ channel blockers such as dihydropyridine, phenylalkylamine and benzothiazepine derivatives. Scatchard analysis of equilibrium binding assays with [3H](+)-PN 200-110, [3H](-)-desmethoxyverapamil [( 3H](-)-D888) and [3H]-d-cis-dilitiazem were consistent with a single class of binding sites for the three radioligands. The pharmacological profile of SR 33557, an original compound with calcium antagonist properties, was investigated using radioligand binding studies. SR 33557 totally inhibited the specific binding of the three main classes of Ca++ channel effectors and interacted allosterically with them. In addition, SR 33557 bound with high affinity to a homogeneous population of binding sites in baboon skeletal muscle.