Apelin has inhibitory effect of endothelium-independent relaxation in the human internal mammary artery

Abstract

Aim: Apelin has important effects on the circulatory system and heart. The main aim of this study was to investigate the effectsof apelin-13 on the contraction induced by norepinephrine (NE), and the endothelium-independent relaxation induced by sodiumnitroprusside (SNP) in human internal mammary artery (IMA) obtained from patients undergoing coronary artery bypass grafting(CABG) surgery.Material and Methods: IMA rings, obtained from patients undergoing CABG surgery, were suspended in isolated tissue bathscontaining Krebs-Henseleit solution, which were continuously gassed with 95% O2 and 5% CO2 at 37°C.Results: The IMA rings were pre-contracted with increasing concentrations of norepinephrine (NE 10-9–10-4 mol/l) and theendothelium-independent relaxation responses to sodium nitroprusside (SNP) were studied. Apelin-13 (10 μM) caused a dosedependentrelaxation in NE pre-contracted IMA rings. Apelin also facilitated the endothelium-independent relaxation induced bySNP.Conclusion: According to the results, apelin facilitated the endothelium-independent relaxation and inhibited the contractile activityof IMA. These results suggest that apelin may be a physiological agent against the deterioration of vascular elasticity caused byendothelial damage especially in atherosclerotic cardiac patients and hypertensive patients.