Stimulation of renal mechanoreceptors and chemoreceptors failed to elicit a renorenal reflex response in spontaneously hypertensive rats compared to normotensive rats, indicating impaired reflexes.
Are renorenal reflexes impaired in spontaneously hypertensive rats compared to normotensive rats?
Renorenal reflexes are impaired in spontaneously hypertensive rats, likely due to a peripheral defect at the level of the renal sensory receptors.
In normotensive Sprague-Dawley rats stimulation of renal mechanoreceptors and chemoreceptors by increasing ureteral pressure and retrograde ureteropelvic perfusion with 0.9 M NaCl results in a contralateral inhibitory renorenal reflex response with contralateral diuresis and natriuresis. Since efferent renal nerve activity is increased in spontaneously hypertensive rats (SHR) and renal denervation delays the onset of hypertension in SHR in association with increased diuresis and natriuresis, the present study was undertaken to examine whether renorenal reflexes were altered in SHR compared with normotensive Wistar-Kyoto rats (WKY). In WKY mean arterial pressure was 113 +/- 2 mm Hg and remained unchanged during renal mechanoreceptor and chemoreceptor stimulation. Increasing ureteral pressure 35 mm Hg increased ipsilateral afferent renal nerve activity 4.5 +/- 1.7 resets/min, decreased contralateral efferent renal nerve activity 3.2 +/- 0.8 resets/min, and increased contralateral urine flow rate 33 +/- 4% and urinary sodium excretion 49 +/- 8%. Similarly, retrograde ureteropelvic perfusion with 0.9 M NaCl increased ipsilateral afferent renal nerve activity 2.5 +/- 0.6 resets/min, decreased contralateral efferent renal nerve activity 2.4 +/- 1.1 resets/min, and increased contralateral urine flow rate 39 +/- 5% and urinary sodium excretion 38 +/- 8%. Stimulating renal mechanoreceptors and chemoreceptors to the same extent in SHR failed to increase ipsilateral afferent renal nerve activity, decrease contralateral efferent renal nerve activity, and produce a contralateral diuresis and natriuresis. It is concluded that renorenal reflexes are impaired in SHR. Failure of ipsilateral afferent renal nerve activity to increase during renal mechanoreceptor and chemoreceptor stimulation indicates a peripheral defect at the level of the renal sensory receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
Kopp et al. (1987) studied Hypertension. Stimulation of renal mechanoreceptors and chemoreceptors vs. Normotensive Wistar-Kyoto rats (WKY) was evaluated on Renorenal reflex response (ipsilateral afferent and contralateral efferent renal nerve activity, contralateral diuresis and natriuresis). Stimulation of renal mechanoreceptors and chemoreceptors failed to elicit a renorenal reflex response in spontaneously hypertensive rats compared to normotensive rats, indicating impaired reflexes.