Effects on regional renal blood flow when unclipping a two-kidney, one-clip hypertensive Wistar rat during renal nerve stimulation.
Blood pressure (BP) is rapidly normalized when removing the obstruction from the renal artery of a two-kidney, one-clip renovascular hypertensive rat (unclipping). This study tested whether efferent renal nerve stimulation (ERNS) of the unclipped kidney affects this drop in BP or the associated changes in diuresis-natriuresis and regional renal blood flow. Three groups of anesthetized renovascular hypertensive Wistar rats were studied: 1) W(C) (time control); 2) W(UC) (unclipped after 30 min); and 3) W(UC+NS) (unclipped after 30 min, with ERNS at 5 Hz for 2 h). Renal excretion and regional hemodynamics (laser Doppler) were monitored in the unclipped kidney. Medullary and cortical blood perfusion increased by 84% and 95%, respectively, in W(UC) 30 min after unclipping (P < .001) but only with 8% and 9%, respectively, in W(UC+NS) (P = NS). Unclipping induced a marked increase in diuresis-natriuresis that was largely unaffected by ERNS. In W(UC) and W(UC+NS) BP returned to normotensive levels within 4 h. However, during the first 30 min, average BP decreased significantly less in W(UC+NS) (9%, 20 mm Hg) than in W(UC) (16%, 35 mm Hg) (P < .05). ERNS at 5 Hz effectively prevented the increase in medullary blood perfusion but did not affect the fall in blood pressure or the pressure diuretic/natriuretic response seen after unclipping. The results suggest that both the reduction in BP and the pressure-induced increase in diuresis/natriuresis seen when unclipping the 2K,1C renovascular hypertensive rat occurs largely independently of ERNS and an increase in medullary blood perfusion.
Rudenstam
J
J
Institute of Physiology and Pharmacology, Department of Physiology, Göteborg University, Sweden.
Karlström
G
G
Göthberg
G
G
Bergström
G
G
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004231:Diuresis / Q000187:drug effects; D004558:Electric Stimulation; D006339:Heart Rate / Q000187:drug effects; D006978:Hypertension, Renovascular / Q000503:physiopathology*; D007668:Kidney / Q000294:innervation* / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012079:Renal Circulation / Q000502:physiology*