Hu You-Min, Fu Ji-Feng, Zhang Zhao, Xu You-Qiu
Department of Physiology, Shanghai Second Medical University, Shanghai 200025, China.
Zhongguo Ying Yong Sheng Li Xue Za Zhi. 2004 Feb;20(1):1-5.
To observe the effect of LPC on the pacemaker current I(f) in ischemic myocardium and if the effect could be reversed by ISO.
By using two microelectrode voltage clamp technique to measure and compare the amplitude of I(f) of ischemic myocardium in the presence of LPC and LPC add ISO.
Ischemia decreased the amplitude of I(f) at all membrane potential levels. Adding LPC 2 x 10(-5) mol/L to the ischemia-like solution, the amplitude of I(f) decreased further (n = 5, P < 0.05), it means that LPC aggravated the inhibitory effect of "ischemia" on the pacemaker activity. Adding LPC 2 x 10(-5) mol/L and ISO 1 x 10(-6) mol/L together to the ischemia-like solution, the amplitude of I(f) increased significantly at membrane potential -90 mV to - 120 mV (n = 8, P < 0.05) compared with ischemia condition, but still did not reach the levels before ischemia.
In acute myocardial ischemia condition, toxic metabolite LPC accentuated its inhibitory effect on pacemaker current I(f), a local release and accumulation of catecholamine could not completely reverse their inhibitory effect.
