Details

Autor(en) / Beteiligte

• NICHOLAS, Christian L
• BEI BEI
• WORSNOP, Christopher
• MALHOTRA, Atul
• JORDAN, Amy S
• SABOISKY, Julian P
• CHAN, Julia K. M
• DUCKWORTH, Ella
• WHITE, David P
• TRINDER, John

Titel

Motor Unit Recruitment in Human Genioglossus Muscle in Response to Hypercapnia

Ist Teil von

• Sleep (New York, N.Y.), 2010-11, Vol.33 (11), p.1529-1538

Ort / Verlag

Darien, IL: American Academy of Sleep Medicine

Erscheinungsjahr

2010

Quelle

Oxford Journals 2020 Medicine

Beschreibungen/Notizen

• single motor unit recordings of the genioglossus (GG) muscle indicate that GG motor units have a variety of discharge patterns, including units that have higher discharge rates during inspiration (inspiratory phasic and inspiratory tonic), or expiration (expiratory phasic and expiratory tonic), or do not modify their rate with respiration (tonic). Previous studies have shown that an increase in GG muscle activity is a consequence of increased activity in inspiratory units. However, there are differences between studies as to whether this increase is primarily due to recruitment of new motor units (motor unit recruitment) or to increased discharge rate of already active units (rate coding). Sleep-wake state studies in humans have suggested the former, while hypercapnia experiments in rats have suggested the latter. In this study, we investigated the effect of hypercapnia on GG motor unit activity in humans during wakefulness. sleep research laboratory. sixteen healthy men. each participant was administered at least 6 trials with P(et)CO(2) being elevated 8.4 (SD = 1.96) mm Hg over 2 min following a 30-s baseline. Subjects were instrumented for GG EMG and respiratory measurements with 4 fine wire electrodes inserted subcutaneously into the muscle. One hundred forty-one motor units were identified during the baseline: 47% were inspiratory modulated, 29% expiratory modulated, and 24% showed no respiratory related modulation. Sixty-two new units were recruited during hypercapnia. The distribution of recruited units was significantly different from the baseline distribution, with 84% being inspiratory modulated (P < 0.001). Neither units active during baseline, nor new units recruited during hypercapnia, increased their discharge rate as P(et)CO(2) increased (P > 0.05 for all comparisons). increased GG muscle activity in humans occurs because of recruitment of previously inactive inspiratory modulated units.