Pressure dependence of exaggerated natriuresis in two-kidney, one clip Goldblatt hypertensive rats.
This study evaluated the responses of each kidney of two-kidney, one clip Goldblatt hypertensive rats to acute volume loading to delineate the contribution of elevated perfusion pressure to the mechanisms of the exaggerated natriuresis in this model of hypertension. Eleven Goldblatt animals (0.2 mm clip 3 weeks prior to study) were studied at spontaneous blood pressure for each kidney's response to volume loading. In 11 other Goldblatt animals an aortic clamp between the renal arteries allowed reduction of perfusion pressure for the left, nonclipped kidney to normal levels. Ten normal rats served as controls. Renal function was examined during control periods and following the infusion of 3.5% body wt of 154 mM X liter-1 NaCl at 22.5 ml X hr-1. An exaggerated natriuresis was observed for the left, nonclipped kidney of the hypertensive Goldblatt rats, while the clipped kidney exhibited an attenuated natriuresis compared to either kidney of normal control rats. Reduction of perfusion pressure to the nonclipped kidney of Goldblatt animals to normal levels resulted in reduced clearance and excretory function before volume loading and attenuated its natriuretic response to levels less than those for the Goldblatt group at spontaneous, hypertensive blood pressure. The exaggerated natriuresis observed at hypertensive blood pressure was attributable to increases of filtered load of Na+ and reduced fractional absorption. These observations indicate that an exaggerated natriuresis occurs in the two-kidney, one clip Goldblatt hypertensive rat and that this phenomenon depends on the elevated renal perfusion pressure to the nonclipped kidney.
D000818:Animals; D001810:Blood Volume; D005919:Glomerular Filtration Rate; D006400:Hematocrit; D006978:Hypertension, Renovascular / Q000503:physiopathology*; D008297:Male; D009318:Natriuresis; D009997:Osmotic Pressure; D051381:Rats; D011919:Rats, Inbred Strains