Effect of omentin on cardiovascular functions and gene expressions in isolated rat hearts.

Objective: Omentin is a recently identified novel adipocytokine mainly expressed in the epicardial adipose tissue. Although it has favorable effects on cardiovascular disease, the impact of omentin on the hearts is still an understudied issue. The aim of the present study was to investigate the possible effects of omentin on isolated rat heart.

Methods: Using the Langendorff method, 28 adult male Sprague-Dawley rat hearts were isolated and perfused with modified Krebs-Henseleit solution (mK-Hs). Concentrations of 100, 200, and 400 ng/mL omentin were given to the hearts for 30 min. The control group (n=7) was perfused with mK-Hs alone. Gene expressions in the left ventricle tissue were determined by real-time polymerase chain reaction. Left ventricular cyclic adenosine monophosphate and cyclic guanosine monophosphate (cGMP) concentrations were determined by using enzyme-linked immunosorbent assay.

Results: All concentrations of omentin significantly decreased left ventricular developed pressure and maximal rate of pressure development that are the indexes of cardiac contractility. At the same time, omentin decreased both phosphoinositide 3-kinase γ (PI3Kγ) and sarcolemmal L-type Ca2+ channel (CaV1.2) mRNA levels. Moreover, this peptide at concentrations of 200 and 400 ng/mL increased endothelial nitric oxide synthase (eNOS) mRNA. Furthermore, concentrations of 200 and 400 ng/mL omentin increased the amount of cGMP.

Conclusion: We conclude that acute omentin treatment decreases cardiac contractility. Elevated eNOS mRNA and cGMP levels with reduced CaV1.2 mRNA are likely to lead to negative inotropy.