[Effects of pethidine on cardiac electrophysiological properties].
To investigate the effects of pethidine on electrophysiological properties of the isolated ventricular myocytes and the underlying mechanism.



Langendorff was applied to perfuse rat heart model and whole-cell current clamp and voltage clamp techniques were used.



Pethidine decreased heart rate (HR) in a concentration dependent manner and caused severe atrioventricular block (AVB) at >or=250 micromol/L. Pethidine reduced action potential amplitude and maximal rate of depolarization, prolonged action potential duration. Pethidine at 100 micromol/L decreased sodium currents (I(Na)), transient outward potassium currents (I(to)), delayed rectifier potassium currents (I(k)) and L-type calcium currents (I(Ca.L)) to (60.7+/-6.9)%, (55.4+/-5.6)%, (65.1+/-8.0)% and (67.4+/-10.1)% of control levels,respectively. These effects could be recovered by washout. Naloxone, an opioid receptor antagonist, could not abolish the effects of pethidine on ionic currents.



Pethidine decreased HR and induced AVB, which may be related to the inhibition of I(Na), I(to), I(k) and I(Ca-L) of heart. The depression of cardiac currents is not mediated by opioid receptor.
Zhang
Xiong
X
Department of Basic Medical Sciences, College of Medical Sciences, Zhejiang University, Hangzhou 310031, China.
Wang
Lin-lin
LL
Ding
Yue-min
YM
Lu
Yuan
Y
Xia
Qiang
Q
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006327:Heart Block / Q000139:chemically induced; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007473:Ion Channels / Q000037:antagonists & inhibitors; D008297:Male; D008614:Meperidine / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000502:physiology
D007473:Ion Channels; D011957:Receptors, Opioid; D008614:Meperidine