Release of 5-hydroxytryptamine by hypoxia from epithelioid cells of chicken thoracic aorta.
Epithelioid cells in the chicken thoracic aorta are shown to contain 5-hydroxytryptamine (5-HT) in immunocytochemical studies. To determine whether these cells act as chemoreceptors, as do type I cells of the carotid body, we examined the effects of hypoxia and acidosis on the release of 5-HT from the chicken thoracic aorta. Hypoxia caused the output of 5-HT in incubation medium. A reduction of pH to 6.8 failed to evoke 5-HT release. The response to hypoxia was inhibited by the removal of extracellular Ca2+ and by nifedipine and omega-conotoxin GVIA. These results suggest that epithelioid cells in the chicken thoracic aorta are chemoreceptors which sense a decrease in PO2 and then release 5-HT by Ca2+ influx through voltage-dependent L- and N-type Ca2+ channels. The epithelioid cells in the chicken aorta may be a useful model for pharmacological and physiological studies of 5-HT-containing cells.
Ito
S
S
Laboratory of Pharmacology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Ohta
T
T
Nakazato
Y
Y
D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015687:Cell Hypoxia; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000378:metabolism*; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D015622:Epithelioid Cells / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism*; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D010455:Peptides; D012701:Serotonin; D020866:omega-Conotoxin GVIA; D009543:Nifedipine; D002118:Calcium