Stroke, Vol 17, 970-975, Copyright © 1986 by American Heart Association
PE Vinall and FA Simeone
The effects of oxygen and glucose deprivation on vasoactivity were
investigated using helical strips of bovine middle cerebral artery.
Hypoxia, created by reducing the PO2 of the bath, or oxidative inhibition
with 2,4 dinitrophenol (DNP) or sodium azide, significantly reduced
contractions induced by serotonin. Normal tonic contractions induced with
fresh and aged whole blood, or 5-HT became phasic and quickly relaxed to
baseline in a hypoxic environment. Glucose elimination from the Krebs
medium, or the inhibition of the glycolytic pathway with iodoacetic acid
(IAA), did not significantly reduce serotonin-induced contractions.
However, contractions were inhibited more with the combination of oxygen
and glucose deprivation, or DNP + IAA, than with oxygen deprivation alone.
Efforts to produce rigor in this preparation by oxygen/substrate reduction
or metabolic inhibition were unsuccessful. Tonic contractions induced by 70
mM potassium became phasic as the Ca++ concentration was reduced.
Contractions resulting from the readdition of Ca++ to arteries exposed to
calcium-free high potassium solution were significantly reduced in the
presence of oxidative and/or glycolytic inhibitors. The uptake of 45Ca++,
as measured by the lanthanum technique, decreased as the bath PO2 was
reduced in both serotonin stimulated and unstimulated arteries. Glucose
deprivation alone did not affect 45Ca++ uptake. This study suggests that
hypoxia has a direct inhibitory affect on cerebral vasoactivity mediated by
reductions in sarcoplasmic Ca++ uptake.
ARTICLES
Effects of oxygen and glucose deprivation on vasoactivity in isolated bovine middle cerebral arteries
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