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Chronic intermittent hypoxia impairs diuretic and natriuretic responses to volume expansion in rats with preserved low-pressure baroreflex control of the kidney
Lucking, Eric F.
O'Halloran, Ken D.
Abdulla, Mohammed H.
American Physiological Society
We examined the effects of exposure to chronic intermittent hypoxia (CIH) on baroreflex control of renal sympathetic nerve activity (RSNA) and renal excretory responses to volume expansion (VE) before and after intra-renal TRPV1 blockade by capsaizepine (CPZ). Male Wistar rats were exposed to 96 cycles of hypoxia per day for 14 days (CIH), or normoxia. Urine flow and absolute Na+ excretion during VE were less in CIH-exposed rats, but the progressive decrease in RSNA during VE was preserved. Assessment of the high-pressure baroreflex revealed an increase in the operating and response range of RSNA and decreased slope in CIH-exposed rats with substantial hypertension (+19mmHg basal mean arterial pressure, MAP), but not in a second cohort with modest hypertension (+12mmHg). Intra-renal CPZ caused diuresis, natriuresis and a reduction in MAP in sham and CIH-exposed rats. Following intra-renal CPZ, diuretic and natriuretic responses to VE in CIH-exposed rats were equivalent to sham. TPRV1 expression in the renal pelvic wall was similar in both experimental groups. Exposure to CIH did not elicit glomerular hypertrophy, renal inflammation or oxidative stress. We conclude that exposure to CIH: 1) does not impair the low-pressure baroreflex control of RSNA; 2) has modest effects on the high-pressure baroreflex control of RSNA, most likely indirectly due to hypertension; 3) can elicit hypertension in the absence of kidney injury; and 4) impairs diuretic and natriuretic responses to fluid overload. Our results suggest that exposure to CIH causes renal dysfunction, which may be relevant to obstructive sleep apnea.
Intermittent hypoxia , Baroreflex , Volume expansion , Diuresis , TPRV1
AlMarabeh, S., O'Neill, J., Cavers, J., Lucking, E. F., O'Halloran, K. D., Abdulla, M. H. (2020) 'Chronic intermittent hypoxia impairs diuretic and natriuretic responses to volume expansion in rats with preserved low-pressure baroreflex control of the kidney', American Journal of Physiology - Renal Physiology. doi: 10.1152/ajprenal.00377.2020
© 2020, American Physiological Society. All rights reserved. This is a post-peer-review, pre-copyedit version of an article published in American Journal of Physiology - Renal Physiology. The final authenticated version is available online at: https://doi.org/10.1152/ajprenal.00377.2020