[The effect of LPC on the pacemaker current I(f) in ischemic myocardium and the influence of ISO on it].

AIM

To observe the effect of LPC on the pacemaker current I(f) in ischemic myocardium and if the effect could be reversed by ISO.

METHODS

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.

RESULTS

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.

CONCLUSION

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.