Effects of ketanserin on the pacemaker activity of rabbit sinus node in vitro.
Electrophysiological effects of ketanserin on pacemaker activity of rabbit sinus node cells were studied using double-microelectrode voltage clamp method. Ketanserin (10(-5) mol/l) caused an increase in spontaneous cycle length accompanied by decreases in the maximum upstroke velocity of the action potential, the slope of the phase 4 depolarization and the action potential amplitude. On the current systems, ketanserin reduced the slow inward current (Isi) and the time-dependent potassium outward current (IK) in a dose-dependent manner. As for a decrease in the outward current, the agent did not change the steady-state activation of IK. These observations indicate that ketanserin does not have a specific effect on a single current system, but that the drug exerts an inhibitory effect on the electrical activity of the sinus node pacemaker cells.
Kotake
H
H
1st Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan.
Hirai
S
S
Kobayashi
M
M
Matsumoto
T
T
Watanabe
M
M
Hasegawa
J
J
Mashiba
H
H
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004594:Electrophysiology; D005260:Female; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D015221:Potassium Channels / Q000187:drug effects; D011817:Rabbits; D012849:Sinoatrial Node / Q000166:cytology / Q000187:drug effects*
D015221:Potassium Channels; D007650:Ketanserin