Metabolic and cardiovascular responses to chronic intermittent hypoxia and hypercapnia

Abstract

Obstructive sleep apnea exposes individuals to chronic intermittent hypoxia‐hypercapnia (CIHH) episodes and it is associated with increases in sympathetic nervous system activity and blood pressure (BP). Previous experimental studies utilized mainly exposure to chronic intermittent hypoxia (CIH) alone without hypercapnia. In this study we examined if CIHH potentiates the pressor and metabolic responses compared to CIH alone. Sprague‐Dawley rats were instrumented with telemetry probes for measuring mean arterial pressure (MAP) and heart rate (HR) 24‐hrs/day. Rats (n=10) were exposed to CIH (7% O2, 8 hrs/day from 8:00–16:00 hours for 5 consecutive days) or CIHH (7% O2 plus 8% CO2, 8 hrs/day from 8:00–16:00 hours for 5 consecutive days). CIHH and CIH reduced food intake similarly (21±1 to 17±1 vs. 16±1 to 14±1 g/day) leading to a net cumulative decrease in food intake of −22 and −21g, respectively. No changes were observed in plasma glucose concentrations. However, MAP response to CIHH was attenuated by 30% compared to CIH alone (+7±1 vs. +10±1 mmHg). CIHH also induced bradycardia when compared to CIH alone (−24±4 vs. +3±4 bpm, respectively). These results show that combining hypoxia with hypercapnia attenuates the rise in MAP and reduces HR without altering blood glucose and food intake when compared to hypoxia alone. Thus, chronic intermittent hypoxia, but not intermittent hypercapnia, appears to contribute to elevated MAP in rats (NHLBI‐PO1HL51971, NIGMS P20GM104357, NIGMS U54GM115428)Support or Funding InformationNHLBI‐PO1HL51971, NIGMS P20GM104357, NIGMS U54GM115428This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.