Modulation of the hypoxic sensory response of the carotid body by 5-hydroxytryptamine: role of the 5-HT2 receptor.
Previous studies have shown that glomus cells of the carotid body express 5-hydroxytryptamine (5-HT). The aim of this study was to elucidate the role of 5-HT on the hypoxic sensory response (HSR) of the carotid body. Sensory activity was recorded from multi-fiber (n=16) and single-fiber (n=8) preparations of ex vivo carotid bodies harvested from anesthetized, adult rats. 5-HT (3 microM) had no significant effect on the magnitude or on the onset of the HSR. However, 5-HT consistently prolonged the time necessary for the sensory activity to return to baseline following the termination of the hypoxic challenge. Ketanserin (40 microM), a 5-HT2 receptor antagonist completely prevented 5-HT-induced prolongation of the HSR, whereas had no effect on the control HSR (onset, magnitude, and time for decay without 5-HT). Carotid bodies expressed 5-HT, but hypoxia did not facilitate 5-HT release. These observations suggest that 5-HT is not critical for the HSR of the rat carotid body, but it modulates the dynamics of the HSR via its action on 5-HT2 receptors.
Jacono
F J
FJ
Department of Medicine, Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA.
Peng
Y-J
YJ
Kumar
G K
GK
Prabhakar
N R
NR
D000200:Action Potentials / Q000187:drug effects / Q000528:radiation effects; D000818:Animals; D002344:Carotid Body / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000378:metabolism; D004563:Electrochemistry; D016166:Free Radical Scavengers / Q000494:pharmacology*; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D044348:Receptors, Serotonin, 5-HT2 / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology*; D058830:Serotonin 5-HT2 Receptor Antagonists; D013997:Time Factors
D016166:Free Radical Scavengers; D044348:Receptors, Serotonin, 5-HT2; D058830:Serotonin 5-HT2 Receptor Antagonists; D012701:Serotonin; D007650:Ketanserin; D004298:Dopamine