Spatiotemporal regulation of the cough motor pattern

Abstract

The purpose of this study was to identify the spatiotemporal determinants of the cough motor pattern. We speculated that the spatial and temporal characteristics of the cough motor pattern would be regulated separately. Electromyograms (EMG) of abdominal muscles (ABD, rectus abdominis or transversus abdominis), and parasternal muscles (PS) were recorded in anesthetized cats. Repetitive coughing was produced by mechanical stimulation of the lumen of the intrathoracic trachea. Cough inspiratory (CTI) and expiratory (CTE) durations were obtained from the PS EMG. The ABD EMG burst was confined to the early part of CTEand was followed by a quiescent period of varying duration. As such, CTEwas divided into two segments with CTE1defined as the duration of the ABD EMG burst and CT E2defined as the period of little or no EMG activity in the ABD EMG. Total cough cycle duration (CTTOT) was strongly correlated with CTE2(r20.8), weakly correlated with CTI(r 2<0.3), and not correlated with CTE1(r 2<0.2). There was no significant relationship between CT Iand CTE1or CTE2. The magnitudes of inspiratory and expiratory motor drive during cough were only weakly correlated with each other (r2<0.36) and were not correlated with the duration of any phase of cough. The results support: a) separate regulation of CTIand CTE, b) two distinct subphases of CTE(CTE1and CTE2), c) the duration of CTE2is a primary determinant of CTTOT, and d) separate regulation of the magnitude and temporal features of the cough motor pattern. © 2009 Wang et al; licensee BioMed Central Ltd.