Chronic Ang II infusion in uninephrectomized rats significantly increased intrarenal Ang II levels (354 vs 164 fmol/g) and systolic pressure, which were prevented by losartan treatment.
Does losartan prevent the augmentation of intrarenal Angiotensin II and development of hypertension in Angiotensin II-infused uninephrectomized rats?
Tasa de eventos absoluta: 354% vs 164%
Chronic low-dose angiotensin II (Ang II) infusion for 13 days mimics two-kidney, one clip Goldblatt hypertension and increase intrarenal Ang II levels. We performed studies to determine the time course for the enhancement of intrarenal Ang II levels and whether the increased intrarenal Ang II is a tissue-specific event and requires a receptor-mediated step. Male Sprague-Dawley rats were uninephrectomized, and either vehicle or Ang II (40 ng/min) was infused via a subcutaneous osmotic minipump. Plasma and renal Ang II levels were measured 3, 7, 10, and 13 days after minipump implantation. Compared with controls (126 +/- 2 mm Hg), systolic pressure in Ang II-infused rats exhibited a detectable increase by day 6 (146 +/- 2 mm Hg) and continued to increase to 189 +/- 5 mm Hg by day 12. Plasma Ang II levels were elevated by day 3, whereas intrarenal Ang II levels were not significantly elevated until 10 days of Ang II infusion. Renal injury characterized by focal and segmental glomerulosclerosis was evident after 13 days of Ang II infusion. Losartan (30 mg/kg per day) prevented the development of hypertension in the Ang II-infused rats for the duration of the infusion period (125 +/- 1 mm Hg) and reduced the degree of glomerular injury. Plasma renin activity was suppressed in the Ang II-infused group but was elevated markedly in both losartan-treated groups. Plasma Ang II levels were elevated in the Ang II-infused rats and were even higher during losartan treatment. Intrarenal Ang II levels were enhanced significantly (354 +/- 60 versus 164 +/- 23 fmol/g) in the Ang II-infused rats. However, losartan treatment prevented the augmentation of intrarenal Ang II caused by Ang II infusion. Heart and adrenal Ang II levels were not significantly increased in the Ang II-infused rats but were significantly elevated during losartan treatment. These results suggest that the tissue-specific elevations of intrarenal Ang II levels caused by chronic Ang II infusion are mediated by angiotensin type 1 receptor activation, which leads to either receptor-mediated internalization of Ang II, enhancement of intrarenal Ang II formation, or both.
Zou et al. (Tue,) conducted a other in Hypertension. Angiotensin II infusion vs. Vehicle was evaluated on Intrarenal Angiotensin II levels. Chronic Ang II infusion in uninephrectomized rats significantly increased intrarenal Ang II levels (354 vs 164 fmol/g) and systolic pressure, which were prevented by losartan treatment.