2001 Fiscal Year Final Research Report Summary
Functional and pathphysiological study in serotonin-containing chemorecptor cells
| Project/Area Number |
12460128
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Basic veterinary science/Basic zootechnical science
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
ITO Shigeo Hokkaido Univ., Grad. School of Vet. Med., Prof., 大学院・獣医学研究科, 教授 (40109509)
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| Co-Investigator(Kenkyū-buntansha) |
OHTA Toshio Hokkaido Univ., Grad. School. of Vet. Med., Asso. Prof., 大学院・獣医学研究科, 助教授 (20176895)
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| Project Period (FY) |
2000 – 2001
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| Keywords | chicken thoracic aorta / 5-hydroxytryptamine / aortic body / voltage-gated channels / aminetransporter / nicotinic ACh receptor / 5-HT release / amine-containing cells |
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| Research Abstract |
Serotonin (5-HT) -containing chemoreceptor cells were characterized using a whole-cell patch clamp technique. (1) 5-HT-containing chemoreceptor cells isolated from chicken thoracic aorta have voltage-gated Na^+ channels, L- and N-type Ca^<2+> channels and K^+ channels including oxygen-sensitive K^+ channels. (2) α-Bungarotoxin-sensitive and insensitive nicotinic ACh receptors were present in these cells. (3) Although we tried to isolate epitherial cells containing 5-HT (neutral red-positive cells) from the guinea-pig and rat intestinal mucosae, we could not obtain the cells responding to voltage-pulses under the voltage-clamp condition. (4) Excess KCl and veratridine evoked 5-HT output from the chicken thoracic aorta, which was inhibited by Ca^<2+> channel antagonists. ACh, nicotine and DMPP also evoked 5-HT output partly inhibited by α-bungarotoxin. (5) p-Chloroamphetamine (PCA) evoked time- and concentration-dependent 5-HT output from the aortic tissues. 5-HT reuptake inhibitors, flu
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voxamine, fluoxetine and clomipramine(CLO) caused a dose-dependent increase in 5-HT in the incubation medium, which were insensitive to extracellular Ca^<2+> removal. (6) CLO and PCA caused a temperature-dependent 5-HT output. CLO-induced 5-HT output was inhibited by extracellular Na^+ removal but not PCA-induced one. (7) 5-HT evoked oscillatory changes in tension and intracellular Ca^<2+> concentration ([Ca^<2+>]i) in the rat basilar artery. In vascular smooth muscles cells isolated from the rat basilar artery, UTP elicited increases in [Ca^<2+>]i in all cells examined, but 5-HT hardly evoked the response. (8) In PC12 cells, a vesicular amine uptake inhibitor, reserpine, decreased the content of dopamine but not ATP in the secretory vesicles. A vesicular H^+-pump ATPase inhibitor, bafilomycine A1, decreased both contents. (9) In adrenal chromaffin cells, both muscarine and caffeine elicited Ca^<2+>-activated K^+ currents concomitant with increases in [Ca^<2+>]i, but caffeine was more effective in eleciting K^+ currents even when both drugs evoked the increase of [Ca^<2+>]i to the same extent. Opioid agonists inhibited voltage-gated Ca^<2+> channels through G proteins. Less
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