Amiloride and KB-R7943 in outward Na+ /Ca2+ exchange current in guinea pig ventricular myocytes.
The reverse mode of Na+/Ca2+ exchange represents an important pathway in inducing Ca2+ overload during ischemia and reperfusion. The inhibitory effects of amiloride and KB-R7943 on Na+/Ca2+ exchange current (INa/Ca) were investigated in guinea pig ventricular myocytes. Whole-cell patch clamp techniques were used under bidirectional ionic conditions and 25 mM of Na+ in pipette solution. At +50 mV, amiloride 10, 30, and 100 microM inhibited the outward INa/Ca by 15, 23, and 41%, respectively; at -80 mV, it inhibited inward INa/Ca by 6, 15, and 23%, respectively. Its inhibitory effect on outward INa/Ca was greater than that on inward INa/Ca. At +50 mV, KB-R7943 1 and 10 microM inhibited the outward INa/Ca by 29 and 61%, respectively; at -80 mV, it inhibited inward INa/Ca by 22 and 57%, respectively. KB-R7943 inhibited both directions of the exchange current with an equal potency. The data suggest that KB-R7943 is not a selective inhibitor on reverse mode of Na+/Ca2+ exchange.
Lu
Jing
J
Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Liang
Yong
Y
Wang
Xiaoliang
X
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000187:drug effects; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors* / Q000502:physiology*; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology*; D016276:Ventricular Function
C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; D019831:Sodium-Calcium Exchanger; D000584:Amiloride; D013890:Thiourea