Proline-rich oligopeptides from Bothrops jararaca ( Bj-PROs) produce potent and long-lasting antihypertensive effect through mechanisms that go beyond ACE inhibition. In this study we evaluated the renal function parameters of spontaneously hypertensive rats (SHR) injected with Bj-PRO-5a and -10c (0.47, 71 or 710 nmol/kg) found in the CNP-precursor of the snake. At 71 and 710 nmol/kg, Bj-PROs increased urinary flow rate (18.1-43.5%). At 71 nmol/kg, Bj-PRO 5a and 10c elevated sodium excretion (68.1 and 40.9%, respectively) and Bj-PRO-5a also increased urinary sodium/creatinine ratio (56.5%). At 0.47 nmol/kg, Bj-PROs did not change renal function. All doses of Bj-PROs reduced blood pressure (Δ = −13 to −24mmHg). We conclude that Bj-PROs reduce blood pressure and improve renal function of SHRs through diuretic and natriuretic mechanisms. [ABSTRACT FROM AUTHOR]