Effects of trimebutine maleate on electrical activities of isolated mammalian cardiac preparations.
The effects of trimebutine maleate on electrical activity in guinea-pig isolated papillary muscles and rabbit sino-atrial nodes have been studied by means of a standard microelectrode method. In papillary muscles, trimebutine (above 10 microM) decreased the maximum rate of rise (Vmax) and the action potential duration at 90% repolarization (APD90), whereas the resting potential was not significantly altered. As to a decrease in Vmax, trimebutine produced a negative shift of the curve relating Vmax to the resting potential along the voltage axis. Trimebutine also depressed the slow action potentials of papillary muscles produced by 27 mM K and 0.2 mM Ba. In spontaneously beating sino-atrial node preparations, trimebutine (above 10 microM) decreased the heart rate, Vmax and the rate of diastolic depolarization. These results indicate that trimebutine maleate possesses a depressant action on the electrical activities of the fast- and slow-response fibres of the heart mainly due to inhibitions of both fast Na+ and slow Ca2+ channels.
Igawa
O
O
1st Department of Internal Medicine, Tottori University, Yonago, Japan.
Kotake
H
H
Hirai
S
S
Hisatome
I
I
Hasegawa
J
J
Mashiba
H
H
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002304:Cardiac Pacing, Artificial; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D010210:Papillary Muscles / Q000187:drug effects; D011817:Rabbits; D012849:Sinoatrial Node / Q000187:drug effects; D014287:Trimebutine / Q000494:pharmacology
D014287:Trimebutine