| Opioids contribute to hypoxia-induced pial artery dilation through activation of ATP-sensitive K+ channels. | |
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MedLine Citation:
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PMID: 7573545 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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It has been previously observed that hypoxia increases cerebrospinal fluid (CSF) methionine enkephalin and leucine enkephalin levels, and these opioids contribute to hypoxia-induced pial artery vasodilation. The present study was designed to investigate whether the activation of ATP-sensitive K+ channels (KATP) mediates the contribution of opioids to the hypoxia-induced pial artery dilation. The closed-cranial window technique was used to measure pial diameter in newborn pigs. Glibenclamide (10(-6) M), a KATP inhibitor, attenuated the dilation resulting from moderate and severe hypoxia [23 +/- 1 and 33 +/- 2% vs. 7 +/- 1 and 18 +/- 2%, respectively, for moderate and severe hypoxia (arterial PO2 approximately 35 and 25 mmHg, respectively) in the absence vs. presence of glibenclamide]. In addition, glibenclamide attenuated the dilation produced by methionine enkephalin (10(-8) and 10(-6) M) (13 +/- 1 vs. 4 +/- 2% and 21 +/- 2 vs. 7 +/- 3%, respectively, for methionine enkephalin in the absence and presence of glibenclamide). Leucine enkephalin-induced dilation was similarly attenuated by glibenclamide. Cromakalim (10(-8) and 10(-6) M), a KATP agonist, produced dilation that was blocked by glibenclamide (12 +/- 1 and 25 +/- 1 vs. 3 +/- 1 and 5 +/- 1% before and after glibenclamide, respectively). These data show that activation of KATP contributes to methionine enkephalin- and leucine enkephalin-induced dilation. Furthermore, these observations suggest that opioids contribute to hypoxia-induced pial artery dilation via KATP activation. |
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Authors:
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V Shankar; W M Armstead |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The American journal of physiology Volume: 269 ISSN: 0002-9513 ISO Abbreviation: Am. J. Physiol. Publication Date: 1995 Sep |
Date Detail:
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Created Date: 1995-11-02 Completed Date: 1995-11-02 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370511 Medline TA: Am J Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: H997-1002 Citation Subset: IM |
Affiliation:
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Department of Anesthesia, University of Pennsylvania, Philadelphia 19104, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine Triphosphate
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pharmacology* Animals Anoxia / physiopathology* Blood Pressure Blood Vessels / drug effects Female Glyburide / pharmacology Male Narcotics / pharmacology* Pia Mater / blood supply* Potassium Channels / drug effects, physiology* Receptors, Opioid / agonists Swine Vasodilation / physiology* Vasodilator Agents / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Narcotics; 0/Potassium Channels; 0/Receptors, Opioid; 0/Vasodilator Agents; 10238-21-8/Glyburide; 56-65-5/Adenosine Triphosphate |
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