Apelin is an endogenous peptide with physiological actions in the cardiovascular system. Apelin can modulate vasomotor tone and is a potent endogenous inotrope. In a series of clinical studies, we have shown that apelin causes peripheral and coronary vasodilatation and increased cardiac contractility. We wish to study and compare the cardiovascular effects of subcutaneous versus intravenous apelin. We specifically wish to determine how different methods of apelin administration affect cardiac output and peripheral vascular resistance in healthy volunteers