Noxious somatic stimuli diminish respiratory-sympathetic coupling by selective resetting of the respiratory rhythm in anaesthetized rats

作者：Korim Willian S; Egwuenu Eyitemi; Fong Angelina Y; McMullan Simon; Cravo Sergio L; Pilowsky Paul M^*

来源：Experimental Physiology, 2012, 97(10): 1093-1104.

DOI：10.1113/expphysiol.2012.066365

Noxious somatic stimulation evokes respiratory and autonomic responses. The mechanisms underlying the responses and the manner in which they are co-ordinated are still unclear. The effects of activation of somatic nociceptive fibres on lumbar sympathetic nerve activity at slow (210 Hz) and fast frequency bands (1001000 Hz) and the effects on respiratorysympathetic coupling are unknown. In anaesthetized, artificially ventilated SpragueDawley rats under neuromuscular blockade, ensemble averaging of sympathetic activity following high-intensity single-pulse stimulation of the sciatic nerve revealed two peaks (similar to 140 and similar to 250 ms) that were present at similar latencies whether or not slow or fast band filtering was used. Additionally, in the slow band of both lumbar and splanchnic sympathetic nerve activity, a third peak with a very slow latency (similar to 650 ms) was apparent. In the respiratory system, activation of the sciatic nerve decreased the expiratory period when the stimulus occurred during the first half of expiration, but increased the expiratory period if the stimulus was delivered in the second half of the expiratory phase. The phase shifting of the respiratory cycle also impaired the respiratorysympathetic coupling in both splanchnic and lumbar sympathetic nerve activity in the subsequent respiratory cycle. The findings suggest that noxious somatosympathetic responses reduce the co-ordination between respiration and perfusion by resetting the respiratory pattern generator.

• 出版日期2012-10