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Activation of #delta#--opioid receptors inhibits L--type Ca~(2+) current and transient outward K~(+) current in rat ventricular myocytes

Lin Yuanyuan, Wu Dongmei, Liu Lei, Liu Qinghua, Yan Zheyi, Wu Bowei

Department of Physiology,Shanxi Medical University.Taiyuan 030001,Shanxi；China

Abstract

In the present study, whole-cell patch-clamp technique was used to observe the effects of SNC162, a selective agonist of #delta#-opioid receptors, on L-type Ca~(2+) current （I_(Ca-L)） and transient outward K~(+) current （I_(to)） in rat ventricular myocytes. The results showed that SNC162 significantly inhibited I_(Ca-L) and Ito in rat ventricular myocytes. The maximal inhibition rate of I_(Ca-L) and Ito reached （46.13±4.12）% and （36.53±10.57）%, respectively. SNC162 at 1×10~(-4) mol/L inhibited the current density of I_(Ca-L) from （8.98±0.40）pA/pF to （4.84±0.44）pA/pF （P〈0.01, n=5） and inhibited that of I_(to) from （18.69±2.42）pA/pF to （11.73±1.67）pA/pF （P〈0.01, n=5）. Furthermore, the effects of naltrindole, a highly selective antagonist of #delta#-opioid receptors, on I_(Ca-L) and I_(to) were also observed. The results showed that naltrindole alone had no effects on I_(Ca-L) and I_(to), while it abolished the inhibitory effects of SNC162 on I_(Ca-L) and I_(to). In conclusion, SNC162 concentration-dependently inhibited I_(Ca-L) and I_(to) in rat ventricular myocytes via activation of the #delta#-opioid receptors, which may be a fundamental mechanism underlying the antiarrhythmic effect of activating #delta#-opioid receptors.

Key words: SNC162;patch-clamp technique;myocytes;cardiac

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Citing This Article：

Lin Yuanyuan, Wu Dongmei, Liu Lei, Liu Qinghua, Yan Zheyi, Wu Bowei. Activation of #delta#--opioid receptors inhibits L--type Ca~(2+) current and transient outward K~(+) current in rat ventricular myocytes. Acta Physiol Sin 2008; 60 (1): 38-42 (in Chinese with English abstract).