title: Stimulus response latency of cough and expiration reflex depends on breathing in the rabbit.
abstract: Expiration reflex and cough may have distinct afferent pathways and/or central integrative mechanisms that may both result in different stimulus response latencies. A newly described method that uses a punctuate mechanical tracheal stimulus to provoke defensive ventilatory reflexes should allow the stimulus response latency to be calculated with reasonable accuracy. The aim of the study was to test whether cough and expiration reflex have different stimulus response latencies. Four hundred and sixty one mechanical tracheal stimulations (50-300 msec) were performed in 21 anesthetized, tracheotomized rabbits. Twenty three percent stimulations (108) provoked a cough reflex and 37% an expiration reflex (171). The individual mean stimulus response latency was computed for each reflex, calculated from stimulus onset to earliest detectable change in ventilatory flow. Cough reflex latency was significantly shorter in inspiration compared to expiration (257±19 msec vs 391±61 msec; p=0.01). In contrast, the expiration reflex latency was significantly shorter in expiration compared to inspiration (210±11 msec vs 329±29 msec, p=0.003). It is concluded that the within breath dependence of the difference in stimulus response latency between cough and expiration reflex is more likely to express different brainstem mechanisms but difference in afferent fibres may not be excluded.
authors.affiliation: Laboratoire de Physiologie, EA 3450 Faculté de Médecine, Université Henri Poincaré, Avenue de la Fôret de Haye, F 54500 Vandoeuvre les Nancy, France. s.varechova@chu-nancy.fr
authors.forename: S
authors.initials: S
authors.lastname: Varechova
authors.forename: M
authors.initials: M
authors.lastname: Poussel
authors.forename: C
authors.initials: C
authors.lastname: Schweitzer
authors.forename: B
authors.initials: B
authors.lastname: Demoulin
authors.forename: B
authors.initials: B
authors.lastname: Chenuel
authors.forename: F
authors.initials: F
authors.lastname: Marchal
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000378:metabolism; D003371:Cough / Q000378:metabolism*; D045853:Exhalation / Q000502:physiology*; D001239:Inhalation / Q000502:physiology*; D011817:Rabbits; D012018:Reflex / Q000502:physiology; D012119:Respiration; D013997:Time Factors; D014132:Trachea