| Objective:The aim of this study was to investigate the effect of Substance P(SP)on L-type calcium current(ICa-L)in rat cardiomyocytes.Background:The neurogenic reaction in acute myocardial ischemia or infarction is accompanied by activation of sympathetic nervous system and by release of neuropeptide such as SP and calcitonin gene related peptide(CGRP)besides norepinephrine(NE).These bioactive transmitters should play some role in the modulation of cardiac function under the condition.The aim of this study was to determine the effects of SP on L-type calcium current in cardioventricular myocytes of rats.Methods:Vertricular myocytes were isolated from SD rats(weighing 260-280g)by retrograde perfusion of the heart via the aorta with an enzyme-containing solution as previous described. Whole-cell patch-clamp recording was made using Apopatch 200B amplifer.Cells were depolarized every 20 s from a holding potential of-40 mV to 0 mV for 300 ms.To establish current-voltage(I-V)curve,stimulating pulses were applied every 2 s at holding potential of -40 mV,depolarizing potential of-40 mV to +40 mV,with 10 mV increment.All experiments were performed at room temperature and solutions were gased with 100%oxygen.All data are expressed as meanSD.Statistical significance was determined using ANOVA test,and P＜0.05 was considered significant.Results:The reduced peak ICa-L(SP 0.1nmol/L 3.26±0.54 pA/pF)was observed,compared to the control(5.51±0.65pA/pF P＜0.05).Substance P induced reduction in peak ICa-Lcould not be attributed to alterations in current-voltage relationships,steady-state activation and inactivation.Conclusions:SP could inhibit ICa-Lin rat cardio-ventricular myocytes,which may protect cardiomyocytes through decrease the muscle contraction,consumption of oxygen and also the concentration of intracellular calcium,reasulting from limitation of calcium current. |
PDF Full Text Request