[3H]Nitrendipine binding to drug receptor sites associated with calcium channels is allosterically regulated by a diverse group of calcium channel antagonists. Verapamil, D-600 (methoxyverapamil), tiapamil, lidoflazine, flunarizine, cinnarizine, and prenylamine all reduce [3H]nitrendipine binding affinity. By contrast, diltiazem, a benzothiazepine calcium channel antagonist, enhances [3H]nitren...

The goal of this study was to determine the effects of the L-type calcium channel blockers verapamil and diltiazem on the currents of voltage-gated potassium channel (fKv1.4ΔN), an N-terminal-deleted mutant of the ferret Kv1.4 potassium channel. Measurements were made using a two electrode voltage clamp technique with channels expressed stably in Xenopus oocytes. The fKv1.4ΔN currents displayed...

The involvement of Ca2+ in the mechanism of the purgative action of rhein anthrone was studied. Among individual or combination pretreatments with calcium channel blockers, calmodulin antagonists and prostaglandin biosynthesis inhibitors, the combination of indomethacin and nifedipine completely blocked the diarrhoea induced by rhein anthrone and also inhibited its effects on colonic fluid and ...

This study examined the effects of different types of calcium channel antagonists on renal haemodynamics and natriuresis. The intravenous infusion of nifedipine (L-type blocker), efonidipine (L/T-type blocker) or mibefradil (predominant T-type blocker) into anaesthetized dogs elicited similar, albeit modest, reductions in blood pressure. Nifedipine (1 microgram.min(-1).kg(-1)) increased renal p...

Calcium antagonists have routinely been assumed to inhibit the contractions of arterial smooth muscle through block of membrane channels. The effects of nifedipine and diltiazem on contractions were examined in in vitro preparations of cattle coronary artery, one of the key therapeutic targets of calcium antagonists, to determine if alternate mechanisms of action are involved. Contractions elic...

PURPOSE To characterize better the ameba-host interactions that may be involved with the pathogenesis of Acanthamoeba keratitis, the role of calcium (Ca2+) on the binding of Acanthamoeba polyphaga to extracellular matrix proteins was examined in vitro. METHODS The binding of a metabolically labeled A. polyphaga (CDC:0187:1) isolate from a case of human keratitis to collagen type IV, laminin, ...

objective(s) calcium-channel blockers have an important role in the treatment of several cardiovascular disorders. derivatives of 1, 4-dihydropyridine are one of the most potent calcium antagonists. in this study four novel ', 4-dihydropyridine calcium channel blockers were synthesized and their hypotensive properties were investigated in male rats. materials and methods four 1, 4-dihydrop...

Pharmacologically distinct calcium channels have been characterized in dissociated cutaneous sensory neurons and motoneurons of the larval lamprey spinal cord. To enable cell identification, sensory dorsal cells and motoneurons were selectively labeled with fluorescein-coupled dextran amine in the intact spinal cord in vitro before dissociation. Calcium channels present in sensory dorsal cells,...

the goal of this study was to determine the effects of the l-type calcium channel blockers verapamil and diltiazem on the currents of voltage-gated potassium channel (fkv1.4δn), an n-terminal-deleted mutant of the ferret kv1.4 potassium channel. measurements were made using a two electrode voltage clamp technique with channels expressed stably in xenopus oocytes. the fkv1.4δn currents displayed...