Abstract: ObjectiveTo investigate the effect of hyperlipidemia on monophasic action potential and calcium current of heart in rabbits.Methods24 rabbits were divided into the high cholesterol group (n=12) and control group (n=12) and fed with high cholesterol forage and standard forage respectively for 10 weeks. Electrocardiograph, ventricular fibrillation threshold and the level of serum lipid were examined. Whole-cell patch clamp technique was used to record I_ Ca-L.ResultsIn high cholesterol group, the serum cholesterol level was higher than the control group ( P<0.01), ventricular fibrillation threshold (10.2±1.7 V) lower than that of the control group (13.9±1.3 V)( P<0.05), MAPD₉₀ displayed more significant rate-dependent prolongation. At cycle lengths of 1500 ms, MAPD₉₀ was 358±18 ms in the high cholesterol group, while it was 277±20 ms in the control group. The densities of I_Ca-L were larger in the high cholesterol group (14.7±0.8 pA/pF) than that in the control group (10.9±1.1 pA/pF)( P<0.01).ConclusionHypercholesterolemia can produce cardiac electrical remodeling, including increased I_Ca-L, prolonged repolarization and decreased ventricular fibrillation thresholds.

Key words: hypercholesterolemia, rabbit, ventricular fibrillation threshold, monophasic action potential, calcium current