Acute intermittent hypoxia induces sympathetic long‐term facilitation but does not alter synchronization between phrenic and sympathetic nerves (1130.15)

Abstract

Acute intermittent hypoxia (AIH) can induce phrenic and sympathetic long‐term facilitation (LTF). Respiration modulates the sympathetic nervous system, leading to an idea that respiratory‐sympathetic coupling plays a role in the generation of sympathetic LTF. To determine if augmentation of synchronization between phrenic and sympathetic nerve activities is necessary to generate sympathetic LTF, we investigated the effect of AIH on phrenic nerve activity (PNA) and renal sympathetic nerve activity (RSNA) using spectral analysis in anesthetized, vagotomized and artificially ventilated Sprague‐Dawley rats (n=6). AIH was performed by ventilation with 10% oxygen for 1min every 6min for a total of 10 hypoxic exposures within an hour. PNA amplitude and RSNA increased by 110% and 100% respectively measured 60 min after AIH (P<0.05). We estimated spectral power of PNA and RSNA and coherence between PNA and RSNA at central respiratory drive frequency, defined as frequency of the main peak in PNA. Spectral power of PNA and RSNA increased by 640% and 270% respectively measured 60 min after AIH (P<0.05). However, coherence between PNA and RSNA did not change from baseline (0.62 +/‐ 0.34) to 60 min after AIH (0.71 +/‐ 0.25). These results suggest that AIH can induce sympathetic LTF in the absence of augmented synchronization between central respiratory drive and RSNA.Grant Funding Source: HL088052