Effect of cilnidipine on L- and T-type calcium currents in guinea pig ventricle and action potential in rabbit sinoatrial node.
Cilnidipine, a dihydropyridine Ca(2+) channel antagonist, is known to have inhibitory effects on both L- and N-type Ca(2+) currents. In the present study, we examined the effect of cilnidipine on myocardial L- and T-type Ca(2+) currents and sinoatrial node action potential configuration. In voltage clamped guinea pig ventricular myocytes, cilnidipine concentration-dependently decreased L- and T-type Ca(2+) currents. In rabbit sinoatrial node tissue, cilnidipine increased cycle length through reduction of phase 4 depolarization slope. In conclusion, cilnidipine has inhibitory effects on T-type Ca(2+) current, which may contribute to its negative chronotropic potency.
Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Kentaro
K
Takeda
Reiko
R
Yamagishi
Haruko
H
Masumiya
Hikaru
H
Tanaka
Koki
K
Shigenobu
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000502:physiology; D020747:Calcium Channels, T-Type / Q000187:drug effects* / Q000502:physiology; D004095:Dihydropyridines / Q000494:pharmacology*; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011817:Rabbits; D012849:Sinoatrial Node / Q000187:drug effects* / Q000502:physiology; D016276:Ventricular Function
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D004095:Dihydropyridines; C065927:cilnidipine