title: Sympathetic regulation of vascular tone via noradrenaline and serotonin in the rat carotid body as revealed by intracellular calcium imaging.
abstract: Hypoxia-induced chemosensory activity in the carotid body (CB) may be enhanced by the sympathetic regulation of vascular tone in the CB. In the present study, we recorded cervical sympathetic nerve activity in rats exposed to hypoxia, and examined noradrenaline (NA)- and serotonin (5-HT)-induced intracellular Ca(2+) ([Ca(2+)]i) responses in smooth muscle cells and pericytes in isolated blood vessels from the CB. Multifiber electrical activity recorded from the cervical sympathetic trunk was increased during the inhalation of hypoxic gas. NA induced [Ca(2+)]i increases in smooth muscle cells in arteriole specimens, whereas 5-HT did not cause any [Ca(2+)]i responses. However, NA did not induce [Ca(2+)]i increases in pericytes in capillaries, whereas 5-HT did and this response was inhibited by the 5-HT2 receptor antagonist, ketanserin. In conclusion, cervical sympathetic nerves enhanced by hypoxia may reduce blood flow in the CB in order to increase chemosensitivity. Thus, hypoxic chemosensitivity in the CB may involve a positive feedback mechanism via sympathetic nerves.
authors.affiliation: Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan; Department of Basic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Yokoyama
authors.affiliation: Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan; Department of Basic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Nakamuta
authors.affiliation: Laboratory for Anatomy and Physiology, Department of Sport and Medical Science, Kokushikan University, Tama, Japan.
authors.forename: Tatsumi
authors.initials: T
authors.lastname: Kusakabe
authors.affiliation: Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan; Department of Basic Veterinary Science, United Graduate School of Veterinary Science, Gifu University, Gifu, Japan. Electronic address: yyoshio@iwate-u.ac.jp.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D000941:Antigens / Q000378:metabolism; D001808:Blood Vessels / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002344:Carotid Body / Q000378:metabolism*; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D000860:Hypoxia / Q000473:pathology / Q000503:physiopathology; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000502:physiology*; D016708:Synaptophysin / Q000378:metabolism; D014365:Tryptophan Hydroxylase / Q000378:metabolism; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D000199:Actins; D000941:Antigens; D002118:Calcium; D004299:Dopamine beta-Hydroxylase; D007650:Ketanserin; D009638:Norepinephrine; D011509:Proteoglycans; D012701:Serotonin; D012702:Serotonin Antagonists; D016708:Synaptophysin; D014365:Tryptophan Hydroxylase; D000099216:Chondroitin Sulfate Proteoglycan 4; C498862:Acta2 protein, rat; C504570:tph1 protein, rat; C504569:tph2 protein, rat
keywords: Carotid body; Noradrenaline; Serotonin; Sympathetic nerve fibers