Abstract
Abstract
One-kidney hypertension (1KH) was produced in rats by placing a clip on one renal artery and removing the other kidney; control rats were uninephrectomized. On Days 4, 8, and 16 after clipping, groups of 1KH and control rats were sacrificed at 8 am, 4 pm, and 12 midnight (MN) and blood was collected for measurements of plasma renin activity (PRA) and plasma aldosterone concentration (PAC). Systolic blood pressures for all groups of 1KH rats were elevated above those of the corresponding control rats. PRA was elevated (P < 0.025) in the clipped rats on Day 4 at all three times (8 am, 4 pm, MN); PRA was not elevated (P > 0.05) on Days 8 and 16 at any time. Circadian variations in PRA were similar in both 1KH and control group on all 3 days with the peak value observed at 4 pm. PAC was elevated (P < 0.025) in the clipped rats on Days 4 and 8 at all times except for MN on Day 4; PAC was not elevated (P > 0.05) on Day 16 at any time. A circadian rhythm for PAC was destroyed in clipped rats and appears distorted in the control rats on Day 4; by Day 16, however, both control and clipped rats demonstrated a circadian rhythm for PAC with the peak at 4 pm. It is concluded that normal circadian variations in PRA and PAC are altered only transiently during the pathogenesis of 1KH in rats.
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