Effect of bile acid on electrophysiological properties of rabbit sino-atrial node in vitro.
1 In order to examine the action of bile acid on cardiac pacemaker activity, the effect of sodium taurocholate (NTC) was studied on the membrane potential and current of rabbit sino-atrial node preparations by means of a double microelectrode voltage clamp technique. 2 In spontaneously beating sino-atrial node preparations, NTC (above 30 microM) decreased the maximum rate of rise of the action potential. Above 100 microM, the compound also exerted a bradycardiac effect and decreased the rate of diastolic depolarization significantly. 3 On the current systems, NTC produced dose-related decreases in the slow inward Ca2+ current and the time-dependent outward K+ current. 4 It is concluded that NTC depresses the spontaneous discharge of the sino-atrial node through decreases in both inward and outward current systems.
Kotake
H
H
1st Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan.
Itoh
T
T
Watanabe
M
M
Hisatome
I
I
Hasegawa
J
J
Mashiba
H
H
D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology*; D004594:Electrophysiology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D011817:Rabbits; D012849:Sinoatrial Node / Q000187:drug effects* / Q000502:physiology; D013656:Taurocholic Acid / Q000494:pharmacology
D001647:Bile Acids and Salts; D013656:Taurocholic Acid