Takehiko Hukuhara

Dopaminergic control of the cough reflex as demonstrated by the effects of apomorphine

The effect of apomorphine on the cough reflex induced by electrical stimulation of the superior laryngeal nerve was studied in cats anesthetized with pentobarbital. Intravenous administration of apomorphine in doses which ranged from 0.1 to 1.0 mg/kg decreased the number of coughs in a dose-dependent manner. Haloperidol (0.3 mg/kg i.v.) did not significantly change the number of coughs. However, haloperidol administered 15 min prior to administration of apomorphine abolished the apomorphine-induced decrease in the number of coughs. These results suggest that dopaminergic mechanisms could have an important role in the regulation of the cough reflex.

LOCALIZATION AND FUNCTIONAL ORGANIZATION OF BULBAR AND PONTINE RESPIRATORY NEURONS IN THE RABBIT

Publisher Summary This chapter focuses on localization and functional organization of bulbar and pontine respiratory neurons in the rabbit. The experiments described in the chapter attempted to investigate the spatial distribution of respiratory unitary discharges in the pons and medulla in paralyzed rabbits by means of a new identification method for respiratory unit activity. Rabbits (40 cases) were vagotomized, paralyzed, and ventilated artificially under local anesthesia. End-tidal O2 and CO2 level were monitored continuously together with arterial blood pressure. All the recorded unit spike potentials were confirmed to be from a soma–dendritic part of a neuron. Location of the microelectrode tip was obtained by the use of stereotaxic coordinates. Respiratory unit activities were identified conventionally on the basis of the spike incidence distribution within the respiratory cycle as revealed by the efferent discharge of the phrenic nerved. In this study, the discharge type of respiratory units was also determined on the basis of the relation to the respiratory phases, defined as the periods of phrenic activity and inactivity by means of cross-correlograms between unit activity and the phrenic nerve discharge.