TIME COURSE STUDY OF BODY-FLUID VOLUMES IN 2-KIDNEY, ONE-CLIP AND ONE-KIDNEY, ONE-CLIP HYPERTENSION IN RATS

Time related changes in distributions of body fluid volumes were studied in rats with either of two types of Goldblatt hypertension; two-kidney, one-clip (2K1C) and one-kidney, one-clip (1K1C) models. Plasma volume (PV), extracellular fluid volume (ECF), and total body water (TBW) were measured on days 1, 7, and 28 after renal artery stenosis. Mean arterial pressure (MAP) and plasma renin activity (PRA) were also determined in conscious rats.In the 2K1C rats each fluid compartment on any experimental day did not differ from the sham controls except for a decrease in PV of the clipped rats on day 1. MAP in the 2K1C increased significantly (p<0.05) only on day 28 as compared with the controls. In the 1K1C rats the tendency toward an increase in PV and ECF on early days was followed by a significant (p<0.05) elevation in ECF on day 28. MAP was higher in the clipped rats than in the controls on days 7 and 28. There were no differences in PRA between the clipped rats and the controls either in 2K1C or 1K1C throughout the study.These results suggest that alterations of body fluid volumes might be involved in the development and maintenance of hypertension in the 1K1C rats, but not in the 2K1C ones. In contrast, the role of the renin-angiotensin system was rather negligible in these two models, as judged from the PRA levels.