Inhibition of Na+/Ca2+ exchange by tetrapeptide FMRFa in intact rat ventricular myocytes
Han, Q.H.; Wu, D.M.; Lu, J.Y.; Wu, B.W.
Yao Xue Xue Bao 36(1): 10-13
2001
ISSN/ISBN: 0513-4870 PMID: 12579852 Document Number: 535754
To study the effects of Phe-Met-Arg-Phe-NH2(FMRFa) on Na+/Ca2+ exchange and its specificity for Na+/Ca2+ exchange in rat ventricular myocytes. Na+/Ca2+ exchange current and other currents of ion channels were measured using whole cell voltage clamp techniques. A dose-related inhibition of tetrapeptide FMRFa on Na+/Ca2+ exchange was observed in rat ventricular myocytes. Inward and outward INa+/Ca2+ were inhibited by 60.1% and 56.5%, respectively, at highest concentration (100 mumol.L-1) and its IC50 were 20 mumol.L-1 and 34 mumol.L-1 in inward and outward INa+/Ca2+, respectively. Inward and outward INa+/Ca2+ were inhibited 38.7% and 34.9%, respectively, at FMRFa 5 mumol.L-1. FMRFa 5 mumol.L-1 and 20 mumol.L-1 did not affect L-type calcium current, sodium current, transient outward current and inward rectifier potassium current. These data indicate that FMRFa is a specific inhibitor of Na+/Ca2+ exchange in intact rat ventricular myocytes.