Differential control of vasomotion by angiotensins in the rostral ventrolateral medulla of hypertensive rats.

The central and peripheral renin?angiotensin systems are known for playing a key role in cardiovascular control. In the present study,we evaluated the hemodynamic effects produced by nanoinjections of angiotensin II (Ang II) or angiotensin-(1?7) [Ang-(1?7)] into the rostral ventrolateral medulla (RVLM) of adult male normotensive (Wistar?WT) and spontaneously hypertensive rats (SHR). Animals were anesthetized (urethane 1.2 g/kg) and instrumented for recording blood pressure (BP), heart rate (HR) and blood flow (BF) in the femoral, renal or mesenteric arteries. Afterwards, rats were positioned in a stereotaxic and prepared for nanoinjections (100 nl) of saline (NaCl 0.9%), Ang-(1?7) (40 ng) or Ang II (40 ng) into the RVLM. The vascular resistance (VR)was calculated by ?MAP/?BF ratio. In WT, Ang-(1?7) or Ang II caused equipotent pressor effects that were not accompanied by changes in vascular resistance. However, MAP changes were greater in SHR. This strain also showed a concomitant increase in relative vascular resistance (?VR/VRbaseline) of renal (0.31 ? 0.07 and 0.3 ? 0.07 vs. 0.02 ? 0.01; Ang-(1?7), Ang II and Saline, respectively) and mesenteric beds (0.3 ? 0.06 and 0.33 ? 0.04 vs. 0.05 ? 0.02; Ang-(1?7), Ang II and saline, respectively). We conclude that Ang II and Ang-(1?7) at the RVLM control the vascular resistance of renal and mesenteric beds during hypertension

Bj-PRO-5a and Bj-PRO 10c found at c-type natriuretic peptide precursor of bothrops jararaca change renal function of hypertensive rats.

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 (? = ?13 to ?24mmHg). We conclude that Bj-PROs reduce blood pressure and improve renal funct