Hyperoxia blunts renal sympathetic nerve activity response to acute intermittent hypercapnia in rats.

Hyperoxia blunts renal sympathetic nerve activity response to acute intermittent hypercapnia in rats. J Physiol Pharmacol. 2019 Oct;70(5): Authors: Madirazza K, Pecotic R, Pavlinac Dodig I, Valic M, Dogas Z Abstract Activation of the sympathetic nervous system plays an important role in the pathophysiology of sleep-related breathing disorders. The aim of the present study was to examine the effects of different levels of hypercapnia in the presence of various background oxygen levels on the magnitude of sympathoexcitation, measured by the renal sympathetic nerve activity (RSNA) in the acute intermittent hypercapnia (AIHc) rat model. The study was conducted on 56 urethane-anesthetized, vagotomized and mechanically ventilated Sprague-Dawley rats (n = 7/group). Each experimental group was subjected to a distinct AIHc protocol that varied in the applied levels of hypercapnia and background oxygen. Mean arterial pressure and RSNA were analyzed in 7 experimental time points: baseline, five hypercapnic episodes (each lasting 3 min) and 15 minutes following the last hypercapnic episode. Exposure to severe hypercapnia (FiCO2 = 0.15) evoked an increase in RSNA, which was preserved throughout the protocol, whereas in moderate hypercapnia (FiCO2 = 0.05) groups there was a trend of progressive diminution of RSNA magnitude following the first hypercapnic episode. Exposure to severe hypercapnia elicited significantly greater RSNA response during fi...
Source: Journal of Physiology and Pharmacology - Category: Drugs & Pharmacology Tags: J Physiol Pharmacol Source Type: research