Renorenal reflexes present in young and captopril-treated adult spontaneously hypertensive rats.
In normotensive Sprague-Dawley rats and Wistar-Kyoto (WKY) rats stimulation of renal mechanoreceptors or chemoreceptors by increasing ureteral pressure or renal pelvic perfusion with 0.9 M NaCl results in a contralateral inhibitory renorenal reflex response with contralateral diuresis and natriuresis. However, in 14-15-week-old spontaneously hypertensive rats (SHR) renal sensory receptor stimulation failed to elicit a contralateral inhibitory renorenal reflex response. The present study was performed to examine whether the lack of a renorenal reflex response in SHR was related to elevated arterial pressure by studying the responses to renal sensory receptor stimulation in 5-6-week-old SHR and in 12-16-week-old SHR that had been treated with captopril from 3 weeks of age to prevent the development of hypertension. In 5-6-week-old SHR, mean arterial pressure was 113 +/- 3 mm Hg. Graded increases of ureteral pressure of 15 and 29 mm Hg resulted in graded increases in ipsilateral afferent renal nerve activity of 57 +/- 22% and 120 +/- 38%. Contralateral urinary sodium excretion increased from 0.26 +/- 0.06 to 0.35 +/- 0.07 mumol/min/g and from 0.36 +/- 0.08 to 0.46 +/- 0.11 mumol/min/g, respectively. In captopril-treated SHR, mean arterial pressure was 109 +/- 3 mm Hg. Increasing ureteral pressure by 34 mm Hg increased ipsilateral afferent renal nerve activity 65 +/- 21% and contralateral urinary sodium excretion from 1.28 +/- 0.24 to 1.53 +/- 0.30 mumol/min/g. Similar results were produced by renal chemoreceptor stimulation. It is concluded that renal sensory receptor stimulation results in a contralateral inhibitory renorenal reflex response in 5-6-week-old SHR and in SHR treated with captopril to prevent the development of hypertension. These results suggest that the previously demonstrated lack of a renorenal reflex response to renal sensory receptor stimulation in hypertensive SHR is related to the maintenance of hypertension.
Kopp
U C
UC
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Smith
L A
LA
D000818:Animals; D001794:Blood Pressure; D002216:Captopril / Q000494:pharmacology*; D002628:Chemoreceptor Cells / Q000502:physiology; D003714:Denervation; D004558:Electric Stimulation; D006339:Heart Rate; D007668:Kidney / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology* / Q000601:surgery; D008465:Mechanoreceptors / Q000502:physiology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012018:Reflex / Q000502:physiology; D012964:Sodium / Q000652:urine; D014554:Urination
D002216:Captopril; D012964:Sodium