Hedrick M S, Dwinell M R, Janssen P L, Pizarro J, Bisgard G E
Department of Biological Sciences, California State University, Hayward, California 94542, USA.
J Appl Physiol (1985). 1998 Apr;84(4):1198-207. doi: 10.1152/jappl.1998.84.4.1198.
The purpose of this study was to test the hypothesis that dysrhythmic breathing induced by the alpha2-agonist clonidine is accompanied by differential recruitment of respiratory muscles. In adult goats (n = 14) electromyographic (EMG) measurements were made from inspiratory muscles (diaphragm and parasternal intercostal) and expiratory muscles [triangularis sterni (TS) and transversus abdominis (Abd)]. EMG of the thyroarytenoid (TA) muscle was used as an index of upper airway (glottal) patency. Peak EMG activities of all spinal inspiratory and expiratory muscles were augmented by central and peripheral chemoreceptor stimuli. Phasic TA was apparent in the postinspiratory phase of the breathing cycle under normoxic conditions. During dysrhythmic breathing episodes induced by clonidine, TS and Abd activities were attenuated or abolished, whereas diaphragm and parasternal intercostal activities were unchanged. There was no tonic activation of TS or Abd EMG during apneas; however, TA activity became tonic throughout the apnea. We conclude that 1) alpha2-adrenoceptor stimulation results in differential recruitment of respiratory muscles during respiratory dysrhythmias and 2) apneas are accompanied by active glottic closure in the awake goat.
α2激动剂可乐定诱发的呼吸节律不齐伴有呼吸肌募集差异。对成年山羊（n = 14）的吸气肌（膈肌和胸骨旁肋间肌）和呼气肌[胸骨三角肌（TS）和腹横肌（Abd）]进行肌电图（EMG）测量。使用甲杓肌（TA）的肌电图作为上呼吸道（声门）通畅的指标。所有脊髓吸气和呼气肌的肌电图峰值活动都因中枢和外周化学感受器刺激而增强。在常氧条件下，呼吸周期的吸气后期可见TA呈阶段性活动。在可乐定诱发的呼吸节律不齐发作期间，TS和Abd的活动减弱或消失，而膈肌和胸骨旁肋间肌的活动未改变。呼吸暂停期间，TS或Abd肌电图无紧张性激活；然而，在整个呼吸暂停期间TA活动变为紧张性。我们得出结论：1）α2肾上腺素能受体刺激在呼吸节律不齐期间导致呼吸肌募集差异，2）清醒山羊的呼吸暂停伴有声门主动关闭。
