title: High affinity binding sites for [3H]-nitrendipine in rabbit uterine smooth muscle.
abstract: The binding properties of the high affinity binding site for [3H]-nitrendipine on rabbit uteri membranes were investigated. The specific component had a dissociation constant of 0.46 +/- .07 nM and a maximal binding of 175 +/- 11 pmol/mg. A variety of other calcium channel blockers inhibited the binding of [3H]nitrendipine with varying potencies. Flunarizine demonstrated a high potency (IC50 = 0.30 microM) in inhibiting binding while verapamil and bepridil were less potent with IC50's of approximately 0.6-1.5 microM. Diltiazem did not displace nitrendipine even at very high concentrations. Verapamil displayed negative cooperative inhibition suggesting that a second site exists on uterine membranes for the binding of other calcium channel blockers.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D002936:Cinnarizine / Q000031:analogs & derivatives / Q000494:pharmacology; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D005260:Female; D005444:Flunarizine; D009130:Muscle, Smooth / Q000378:metabolism*; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D009568:Nitrendipine; D011817:Rabbits; D014599:Uterus / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D002936:Cinnarizine; D009568:Nitrendipine; D014700:Verapamil; D009543:Nifedipine; D005444:Flunarizine