Effects of diacetyl guan-fu base A on pacemaker cells in sinoatrial node of rabbits.
OBJECTIVE
To study the electrophysiological effects of diacetyl guan-fu base A (DGFA) on pacemaker cells in sinoatrial (SA) node.


METHODS
Intracellular microelectrode method was used to record parameters of action potential (AP) in SA node of rabbits.


RESULTS
DGFA could not only slow down spontaneous firing frequency (SFF), mean rate of repolarization (MRR), and rate of diastolic depolarization (RDD), but also prolong diastolic interval (DI) and duration of action potential (APD) in a concentration-dependent manner in SA node. Furthermore, DGFA markedly decreased the maximum rate of depolarization (MRD) with a slight reduce of the amplitude of action potential (APA) and there was no significant effect on the maximal diastolic potential (MDP). The decrease in SFF caused by DGFA was not affected by atropine (0.05 mg/L).


CONCLUSIONS
The effects might be due to the reduction of calcium influx and potassium efflux, and the muscarinic receptors were not involved.
Sun
Hua
H
Department of Pharmacology, College of Pharmacy, Shandong University, Jinan 250012, China.
Zhang
Qing-Zhu
QZ
Wang
Ru-Bin
RB
Ji
Jian-Bo
JB
D000200:Action Potentials / Q000187:drug effects; D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D004594:Electrophysiology; D005260:Female; D008297:Male; D011817:Rabbits; D012849:Sinoatrial Node / Q000166:cytology* / Q000502:physiology
D000470:Alkaloids; C119184:diacetyl guan-fu base A