Development of original metabolically stable apelin-17 analogs with diuretic and cardiovascular effects

Apelin, a (neuro)vasoactive peptide, plays a prominent role in controlling cardiovascular functions and water balance. Because the in vivo apelin half-life is in the minute range, we aimed to identify metabolically stable apelin-17 (K17F) analogs. We generated P92 by classic chemical substitutions and LIT01-196 by original addition of a fluorocarbon chain to the N terminus of K17F. Both analogs were much more stable in plasma (half-life >24 h for LIT01-196) than K17F (4.6 min). Analogs displayed a subnanomolar affinity for the apelin receptor and behaved as full agonists with regard to cAMP production, ERK phosphorylation, and apelin receptor internalization. Ex vivo, these compounds induced vasorelaxation of rat aortas and glomerular arterioles, respectively, precontracted with norepinephrine and angiotensin II, and increased cardiac contractility. In vivo, after intracerebroventricular administration in water-deprived mice, P92 and LIT01-196 were 6 and 160 times, respectively, more efficient at inhibiting systemic vasopressin release than K17F. Administered intravenously (nmol/kg range) in normotensive rats, these analogs potently increased urine output and induced a profound and sustained decrease in arterial blood pressure. In summary, these new compounds, which favor diuresis and improve cardiac contractility while reducing vascular resistances, represent promising candidates for the treatment of heart failure and water retention/hyponatremic disorders.