Apelin Antagonizes Myocardial Impairment in Sepsis

Background: Apelin is a cardiovascular peptide with multiple functions regulating homeostasis of the circulatory system and is the endogenous ligand of angiotensin II receptor like-1 (AGTRL1). Apelin has anti-inflammatory and inhibitory effects on release of inflammatory mediators. We aimed to analyze whether apelin antagonizes myocardial impairment in sepsis by attenuating inflammatory responses. Methods and Results: Male rats underwent sepsis by cecal ligation and puncture (CLP) after receiving low- or high-dose apelin for 3 days. Twenty hours later, rats with sepsis showed severe disturbance of hemodynamic features. Reverse transcription-polymerase chain reaction revealed decreased mRNA levels of apelin and AGTRL1 in myocardia of rats with sepsis. Enzyme immune assay detected a lower level of apelin in plasma and myocardia. Western blot analysis revealed decreased level of myocardial AGTRL1 protein. Low- and high-dose apelin administration ameliorated disorders of cardiac function: increased mean arterial blood pressure, attenuated heart rate, elevated +LVdp/dt(max) and LVdp/dt(max), and lowered left ventricular end-diastolic pressure. Rats treated with low- or high-dose apelin showed lower content of plasma monocyte chemoattractant protein land interleukin 8. In cultured rat peritoneal macrophages, apelin directly inhibited the production of monocyte chemoattractant protein 1 and interleukin-8 induced by lipopolysaccharide. Conclusions: These results suggest that apelin antagonizes cardiac impairment in sepsis by attenuating inflammatory responses and might be a promising therapeutic target for severe sepsis and septic shock. (J Cardiac Fail 2010:16:609-6/7)