Abstract

Aim: Apelin has important effects on the circulatory system and heart. The main aim of this study was to investigate the effects
of apelin-13 on the contraction induced by norepinephrine (NE), and the endothelium-independent relaxation induced by sodium
nitroprusside (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 baths
containing 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 the
endothelium-independent relaxation responses to sodium nitroprusside (SNP) were studied. Apelin-13 (10 μM) caused a dosedependent
relaxation in NE pre-contracted IMA rings. Apelin also facilitated the endothelium-independent relaxation induced by
SNP.
Conclusion: According to the results, apelin facilitated the endothelium-independent relaxation and inhibited the contractile activity
of IMA. These results suggest that apelin may be a physiological agent against the deterioration of vascular elasticity caused by
endothelial damage especially in atherosclerotic cardiac patients and hypertensive patients.

Key words: Apelin; Nitroprusside; Internal Mammary Artery; Coronary Artery Bypass.