Potencies of doxapram and hypoxia in stimulating carotid-body chemoreceptors and ventilation in anesthetized cats.
The effects of doxapram on carotid chemoreceptor activity and on ventilation (phrenic-nerve activity) were tested before and after denervation of the peripheral chemoreceptors in cats. Doxapram was found to be a potent stimulus to the carotid chemoreceptors; the stimulation produced by 1.0 mg/kg doxapram, iv, equalled that produced by a Pao2 of 38 torr. Doxapram also increased phrenic-nerve activity in doses as low as 0.2 mg/kg, iv. After denervation of the peripheral chemoreceptors, doxapram in doses as large as 6 mg/kg failed to stimulate ventilation. It is concluded that (in anesthetized cats) doxapram in doses of less than 6 mg/kg increases ventilation by direct stimulation of the carotid, and, probably, the aortic, chemoreceptors, not by a direct effect on the medullary respiratory center.
D000758:Anesthesia; D000818:Animals; D001011:Aorta / Q000294:innervation; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D002344:Carotid Body / Q000187:drug effects*; D002346:Carotid Sinus / Q000294:innervation; D002415:Cats; D002698:Chloralose / Q000008:administration & dosage; D003714:Denervation; D004315:Doxapram / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D000860:Hypoxia / Q000503:physiopathology*; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D009476:Neurons, Efferent / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010791:Phrenic Nerve / Q000502:physiology; D012119:Respiration / Q000187:drug effects*; D014140:Tracheotomy; D014520:Urethane / Q000008:administration & dosage
D002245:Carbon Dioxide; D002698:Chloralose; D014520:Urethane; D004315:Doxapram; D010100:Oxygen