| Carotid body chemoreception in the absence and presence of CO2-HCO3-. | |
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MedLine Citation:
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PMID: 1667617 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Carotid body (CB) chemosensory responses to natural and pharmacological stimuli were studied in vitro in the presence and nominal absence of CO2-HCO3- in the perfusion-superfusion media. The CBs obtained from cats (n = 10), anesthetized with sodium pentobarbitone, were simultaneously perfused and superfused with a modified Tyrode solution at 36.5 +/- 0.5 degrees C, equilibrated respectively with PO2 of 120 and less than 20 Torr. The Tyrode, nominally free of CO2-HCO3- (HEPES-NaOH, pH 7.38, 310 mOsm), was used first. Subsequently the Tyrode containing HEPES-HCO3-, equilibrated with PCO2 of 36.8 Torr (pH 7.38) was used. Chemosensory discharges were recorded from the carotid sinus nerve. Both hypoxia (PO2 = 20-25 Torr) and ischemic hypoxia stimulated the discharge in the absence and presence of CO2-HCO3-. However, the presence of CO2-HCO3- significantly raised the baseline activity, augmented the speed, sensitivity and the maximal responses to both types of hypoxia. Hypercapnic perfusate (PCO2 = 65 Torr at pH 7.17) produced a peak response equally promptly in the absence and presence of CO2-HCO3- in the ongoing perfusate but generated a larger and more sustained response. Presence of CO2-HCO3- strongly potentiated the responses to cyanide (10(-10)-10(-7) mol) but less strikingly the responses to nicotine (10(-11)-10(-8) mol). Thus, the extracellular CO2-HCO3- significantly improved the response to hypoxia but was not essential for O2 chemoreception. The underlying mechanisms of the effect of CO2-HCO3- is likely to be mediated by the Cl(-)-HCO3- anion exchanger in the pH regulation of glomus cells. |
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Authors:
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R Iturriaga; S Lahiri |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Brain research Volume: 568 ISSN: 0006-8993 ISO Abbreviation: Brain Res. Publication Date: 1991 Dec |
Date Detail:
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Created Date: 1992-06-23 Completed Date: 1992-06-23 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 0045503 Medline TA: Brain Res Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 253-60 Citation Subset: IM |
Affiliation:
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Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia 19104-6085. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Anoxia Bicarbonates / pharmacology* Carbon Dioxide / pharmacology* Carotid Body / drug effects, physiology* Cats Chemoreceptor Cells / drug effects, physiology* Dose-Response Relationship, Drug Female Male Nicotine / pharmacology Partial Pressure Perfusion Sodium Cyanide / pharmacology Time Factors |
| Grant Support | |
ID/Acronym/Agency:
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HL-19737/HL/NHLBI NIH HHS; HL-43413/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Bicarbonates; 124-38-9/Carbon Dioxide; 143-33-9/Sodium Cyanide; 54-11-5/Nicotine |
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