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[Effects of pethidine on cardiac electrophysiological properties]
Xiong Zhang1, Lin-lin Wang, Yue-min Ding
1Department of Basic Medical Sciences, College of Medical Sciences, Zhejiang University, Hangzhou 310031, China.
Objective:
To investigate the effects of pethidine on electrophysiological properties of the isolated ventricular myocytes and the underlying mechanism.
Methods:
Langendorff was applied to perfuse rat heart model and whole-cell current clamp and voltage clamp techniques were used.
Results:
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.
Conclusion:
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.