Linked Life Data

9507150

Source:http://linkedlifedata.com/resource/pubmed/id/9507150

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-5-4
pubmed:abstractText
Our previous studies have indicated that oxygen radicals, produced during reoxygenation following short-term arterial hypoxia, lead to sustained suppression of cerebral arteriolar responses to N-methyl-D-aspartate (NMDA). However, whether arteriolar dilator responses to NMDA are reduced during arterial hypoxia has never been examined. In this study, we determined whether hypoxia or hypoxia-related metabolites such as adenosine or nitric oxide (NO) will reduce NMDA-induced arteriolar dilation. We have also determined the location of NMDA receptor- and brain nitric oxide synthase (bNOS)-positive neurons in the cerebral cortex. In anesthetized piglets, pial arteriolar diameters were determined using intravital microscopy. Baseline arteriolar diameters were approximately 100 microns. Topical application of NMDA at concentrations of 10(-5), 5 x 10(-5) and 10(-4) M resulted in dose-dependent vasodilation (9 +/- 2, 18 +/- 2 and 29 +/- 2% above baseline, respectively, n = 21). Administration of theophylline (20 mg/kg, i.v.) had no effect on NMDA-dependent vasodilation, but it did block dilation to hypoxia (inhalation of 8.5% O2). In theophylline-treated animals, NMDA responses were completely abolished during hypoxia (28 +/- 2 vs. 2 +/- 1%, respectively to 10(-4) M, n = 7) while sodium nitroprusside (SNP, 10(-4) M) still dilated pial arterioles normally. NMDA-induced vasodilation was not modified after application and removal of adenosine (10(-4) M; n = 5) or SNP (10(-5) M; n = 4), or when SNP (10(-7) M) was coapplied with NMDA (n = 6). Conversely, coapplication of adenosine (10(-6) M) attenuated NMDA responses (31 +/- 5 vs. 20 +/- 3%, n = 7). We also found that NMDA receptor- and bNOS-containing neurons were located predominantly in layers II/III of the cortex. Proximity of these neurons to the cortical surface is consistent with diffusion of NO to pial arterioles as the mechanism of dilation to NMDA. We conclude that NMDA-induced cerebral arteriolar dilation is inhibited by hypoxia alone and by exogenous adenosine, but not by NO.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-8993
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
780
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
237-44
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:9507150-Adenosine, pubmed-meshheading:9507150-Animals, pubmed-meshheading:9507150-Animals, Newborn, pubmed-meshheading:9507150-Anoxia, pubmed-meshheading:9507150-Cerebral Arteries, pubmed-meshheading:9507150-Cerebral Cortex, pubmed-meshheading:9507150-Cerebrovascular Circulation, pubmed-meshheading:9507150-Excitatory Amino Acid Agonists, pubmed-meshheading:9507150-Female, pubmed-meshheading:9507150-Immunohistochemistry, pubmed-meshheading:9507150-Male, pubmed-meshheading:9507150-N-Methylaspartate, pubmed-meshheading:9507150-Nitric Oxide, pubmed-meshheading:9507150-Nitroprusside, pubmed-meshheading:9507150-Pia Mater, pubmed-meshheading:9507150-Receptors, N-Methyl-D-Aspartate, pubmed-meshheading:9507150-Swine, pubmed-meshheading:9507150-Theophylline, pubmed-meshheading:9507150-Vasodilator Agents
pubmed:year
1998
pubmed:articleTitle
Inhibitory effects of hypoxia and adenosine on N-methyl-D-aspartate-induced pial arteriolar dilation in piglets.
pubmed:affiliation
Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't