Cardiovascular effects of intravenous ghrelin infusion in healthy young men

1 Medical Department M (Endocrinology and Diabetes), Aarhus University Hospital; 2 Research Laboratory for Biochemical Pathology, Institute of Pathology, Aarhus University Hospital; 3 Department of Cardiology, Aarhus University Hospital, Skejby Sygehus; and 4 Department of Anesthesiology and Intensive Care, Aarhus University Hospital, Skejby Sygehus, Aarhus, Denmark Submitted 25 April 2007 ; accepted in final form 10 September 2007 Ghrelin infusion improves cardiac function in patients suffering from cardiac failure, and bolus administration of ghrelin increases cardiac output in healthy subjects. The cardiovascular effects of more continuous intravenous ghrelin exposure remain to be studied. We therefore studied the cardiovascular effects of a constant infusion of human ghrelin at a rate of 5 pmol/kg per minute for 180 min. Fifteen healthy, young (aged 23.2 ± 0.5 yr), normal-weight (23.0 ± 0.4 kg/m 2 ) men volunteered in a randomized double-blind, placebo-controlled crossover study. With the subjects remaining fasting, peak myocardial systolic velocity S', tissue tracking TT, left ventricular ejection fraction EF, and endothelium-dependent flow-mediated vasodilatation were measured. Ghrelin infusion increased S' 9% ( P = 0.002) and TT 10% ( P < 0.001), whereas EF, resting blood flow velocity, and endothelium-dependent flow-mediated vasodilatation did not change ( P = 0.13). This was associated with a peak in serum growth hormone after 60 min of infusion (37.77 ± 5.27 ng/ml, P < 0.001), a doubling of free fatty acid levels ( P = 0.001), and a 1.6-fold increase in cortisol levels ( P < 0.05), whereas glucose and catecholamine levels were constant. In conclusion, supraphysiological levels of ghrelin stimulate left ventricular function in terms of S' and TT in healthy young normal-weight men without changing resting blood flow velocity and endothelium-dependent flow-mediated vasodilatation. The effects did not translate into detectable increments in EF. left ventricular function; tissue Doppler imaging; tissue tracking; endothelium-dependent flow-mediated vasodilatation Address for reprint requests and other correspondence: E. T. Vestergaard, Medical Dept. M (Endocrinology and Diabetes), Aarhus Univ. Hospital, DK-8000 Aarhus C, Denmark (e-mail: e.t.vestergaard{at}ki.au.dk )