Lack of renoprotective effect of chronic intravenous angiotensin-(1-7) or angiotensin-(2-10) in a rat model of focal segmental glomerulosclerosis.

Abstract

Unopposed angiotensin (Ang) II-mediated cellular effects may lead to progressive glomerulosclerosis. While Ang-II can be locally generated in the kidneys, we previously showed that glomerular podocytes primarily convert Ang-I, the precursor of Ang-II, to Ang-(1-7) and Ang-(2-10), peptides that have been independently implicated in biological actions opposing those of Ang-II. Therefore, we hypothesized that Ang-(1-7) and Ang-(2-10) could be renoprotective in the fawn-hooded hypertensive rat, a model of focal segmental glomerulosclerosis. We evaluated the ability of 8-12 week-long intravenous administration of either Ang-(1-7) or Ang-(2-10) (100-400 ng/kg/min) to reduce glomerular injury in uni-nephrectomized fawn-hooded hypertensive rats, early or late in the disease. Vehicle-treated rats developed hypertension and lesions of focal segmental glomerulosclerosis. No reduction in glomerular damage was observed, as measured by either 24-hour urinary protein excretion or histological examination of glomerulosclerosis, upon Ang-(1-7) or Ang-(2-10) administration, regardless of peptide dose or disease stage. On the contrary, when given at 400 ng/kg/min, both peptides induced a further increase in systolic blood pressure. Content of Ang peptides was measured by parallel reaction monitoring in kidneys harvested at sacrifice. Exogenous administration of Ang-(1-7) and Ang-(2-10) did not lead to a significant increase in their corresponding intrarenal levels. However, the relative abundance of Ang-(1-7) with respect to Ang-II was increased in kidney homogenates of Ang-(1-7)-treated rats. We conclude that chronic intravenous administration of Ang-(1-7) or Ang-(2-10) does not ameliorate glomerular damage in a rat model of focal segmental glomerulosclerosis and may induce a further rise in blood pressure, potentially aggravating glomerular injury.