title: Dopaminergic influence on the ventilatory response to sustained hypoxia in the cat.
abstract: We examined the effects of the dopamine blocker haloperidol (H) on the ventilatory response to sustained hypoxia in awake cats. Ventilation (VE) was measured plethysmographically, and end-tidal PO2 (PETO2) and PCO2 were measured by sampling tracheal gas. Measurements were made before, during, and after 30 min of isocapnic hypoxia after pretreatment with 0.1 mg/kg of H and placebo (P). Experimental runs were conducted on separate days with the P day being first. Two levels of hypoxia were employed. Six cats were studied at a PETO2 of approximately 61 Torr, and six cats were studied at a PETO2 of approximately 41 Torr. In all experiments, isocapnia was maintained and end-tidal PCO2 did not differ on the H and P days. With mild hypoxia after P, VE increased to 137% of air breathing control in the first 5 min of hypoxia and then declined to 102% of control at 25 min of hypoxia. Results on the H day were similar. With more severe hypoxia after P, VE increased to 173% of control at 5 min and then declined to 127% of control. With H, VE increased to 172% of control in the first 5 min and then declined to 149% of control at 25 min. After 25 min of more severe hypoxia, both VE and tidal volume were significantly greater with H than with P (P < 0.05). H reduced the ventilatory decline observed with more severe hypoxia but had no effect on the ventilatory decline in milder hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Manitoba, Winnipeg, Canada.
authors.forename: W
authors.initials: W
authors.lastname: Long
authors.forename: N R
authors.initials: NR
authors.lastname: Anthonisen
mesh_terms: D000818:Animals; D002415:Cats; D002628:Chemoreceptor Cells / Q000187:drug effects*; D004298:Dopamine / Q000378:metabolism*; D006220:Haloperidol / Q000494:pharmacology*; D000860:Hypoxia / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D007273:Injections, Intramuscular; D013058:Mass Spectrometry; D010991:Plethysmography; D012119:Respiration / Q000187:drug effects* / Q000502:physiology; D012129:Respiratory Function Tests
chemical_list: D006220:Haloperidol; D004298:Dopamine