Sex difference in the repolarization currents of rabbit ventricular cells.
The current difference between male and female rabbit ventricular myocytes was investigated for elucidating the mechanism of longer QT interval and higher incidence of drug-associated torsade de pointes in female rabbits than in male rabbits. Whole cell patch clamp technique was used to record APD, Ito, IK,tail, IK1 and ICa,L of myocytes from left ventricular apex. There was no difference in the membrane capacitance between male and female rabbit myocytes. APD90 was longer in female rabbits (560.4+/-26.5 ms, n=15) than in male ones (489.0+/-20.7 ms, n = 14), P<0. 05. In female rabbit myocytes, IKtail, Ito, IK1 and ICa,L were 0.71+/-0.05 pA/pF (n=17), 8.28+/-1.03 pA/pF (n=18), 24.5+/-3.6 pA/pF (n=12) and 9.0+/-2.3 pA/pF (n=15) respectively. In male rabbit myocytes, they were 0.84+/-0.07 pA/pF (n=18), 8.60+/-1.20 pA/pF (n=18), 25.9+/-4.5 pA/pF (n=14) and 9.3+2.6 pA/pF (n=16) respectively. IK,tail in female rabbits was significantly lower than that of male rabbits (P<0.05), but there was no difference in Ito,IK1 and ICa.L between male rabbits and female rabbits (P>0.05). The lower IK.tail of female rabbit myocytes may contribute to the longer repolarization and the higher incidence of drug-associated torsade de pointes.
Ruan
Yanfei
Y
Department of Cardiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Liu
Nian
N
Zhou
Qiang
Q
Li
Yang
Y
Wang
Lin
L
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D005260:Female; D008297:Male; D032383:Myocytes, Cardiac / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology; D011817:Rabbits; D012727:Sex Characteristics; D016171:Torsades de Pointes / Q000139:chemically induced; D016276:Ventricular Function
D015221:Potassium Channels