The response of few-fiber carotid chemoreceptor preparations to almitrine in the dog.

Almitrine, a long-lasting peripheral chemoreceptor stimulant, was given to nine dogs via intracarotid injection. Carotid chemoreceptor activity was recorded from single or few-fiber afferent nerve preparations. Doses of 10-20 microgram/kg were generally sufficient to produce a brisk stimulatory response of less than 30 min duration. In four dogs decreasing arterial PO2 was found to allow a greater than additive response to almitrine. Infusions of NaHCO3 appeared to depress the response to almitrine whereas changing arterial PCO2 had little effect on the carotid chemoreceptor response to almitrine. Neither dopamine infusion nor dopamine receptor blockade altered the responsiveness of the carotid chemoreceptors to almitrine.