Πέμπτη 3 Αυγούστου 2017

Hypercapnia-induced active expiration increases in sleep and enhances ventilation in unanaesthetized rats

Abstract

Expiration is passive at rest but becomes active through recruitment of abdominal muscles under increased respiratory drive. Hypercapnia-induced active expiration has not been well explored in unanaesthetized rats. We hypothesized that (i) CO2-evoked active expiration is recruited in a state-dependent manner i.e. differently in sleep or wakefulness and (ii) that recruitment of active expiration enhances ventilation, hence having an important functional role in meeting metabolic demand. To test these hypotheses Wistar rats (280–330 g) were implanted with electrodes for electroencephalography (EEG) and electromyography (EMG) of the neck, diaphragm (DIA) and abdominal (ABD) muscles. Active expiratory events were considered as rhythmic ABDEMG activity interposed to DIAEMG. Animals were exposed to room air followed by hypercapnia (7% CO2) with EEG, EMG and ventilation (V̇E) recorded throughout the experimental protocol. No active expiration was observed during room air exposure. During hypercapnia, CO2-evoked active expiration was predominantly recruited during non-REM sleep. Its increased occurrence during sleep was evidenced by the decreased DIA-to-ADB ratio (1:1 ratio means that each DIA event is followed by an ABD event, indicating a high occurrence of ABD activity). Moreover, V̇E was also enhanced (P < 0.05) in periods with active expiration. V̇E had a positive correlation (P < 0.05) with the peak amplitude of ABDEMG activity. The data strongly demonstrate that hypercapnia-induced active expiration increases during sleep and provide an important functional role to support V̇E in conditions of increased respiratory demand.

This article is protected by copyright. All rights reserved



from Physiology via xlomafota13 on Inoreader http://ift.tt/2upL81j
via IFTTT

Δεν υπάρχουν σχόλια:

Δημοσίευση σχολίου

Σημείωση: Μόνο ένα μέλος αυτού του ιστολογίου μπορεί να αναρτήσει σχόλιο.