Contribution of L-type Ca2+ channel to the regulation of coronary arterial smooth muscle contraction is different in rats and mice

Background L-type calcium channel participates in the regulation of a variety of physical and pathological process.In vasculature,it mainly mediated agonist-induced vascular smooth muscle contraction.However,it is not clear whether there are differences in L-type calcium channel mediated vessel responses to certain vasoconstrictors among different species.Methods The coronary arteries were dissected from the heart of rats and mice respectively.The coronary arterial ring contraction was measured by Multi Myograph System.Results Endothelin-1,U46619 and 5-HT could produce concentration-dependent vasoconstriction of coronary arterial rings from rats and mice.Compared with rats,the vessel rings of mice were more sensitive to ET-1and U46619,and less sensitive to 5-HT.The L-type Ca2+channel blocker nifedipine could significantly inhibit the coronary artery contractions induced by ET-1,U46619 and 5-HT.The inhibitory effect of 1μM nifedipine on ET-1 and 5-HT-induced coronary artery contractions were stronger in mice than in rats,but its effect on U46619 induced-vessel contractions was much weaker in mice than in rats.Conclusions L-type Ca2+channel plays an important role in the coronary arterial contraction,but the responses to vasoconstrictor and L-type Ca2+channel blocker are different between rats and mice,thus suggesting that the coronary arteries of rats and mice have different biological characteristics.