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Dietrich HH, Ellsworth ML, Sprague RS, Dacey RG Jr. Red
blood cell regulation of microvascular tone through adenosine triphosphate. Am
J Physiol Heart Circ Physiol. 2000;Apr;278(4):H1294-298.
Department of Neurological Surgery, School of Medicine, Washington
University, St. Louis 63110, Missouri.
The matching of blood flow with metabolic need requires a mechanism
for sensing the needs of the tissue and communicating that need to the
arterioles, the ultimate controllers of tissue perfusion. Despite significant
strides in our understanding of blood flow regulation, the identity of
the O(2) sensor has remained elusive. Recently, the red blood cell, the
Hb-containing O(2) carrier, has been implicated as a potential O(2) sensor
and contributor to this vascular control by virtue of its concomitant
carriage of millimolar amounts of ATP, which it is able to release when
exposed to a low-O(2) environment. To evaluate this possibility, we exposed
perfused cerebral arterioles to low extraluminal O(2) in the absence
and presence of red blood cells or 6% dextran and determined both vessel
diameter and ATP in the vessel effluent. Only when the vessels were perfused
with red blood cells did the vessels dilate in response to low extraluminal
O(2). In addition, this response was accompanied by a significant increase
in vessel effluent ATP. These findings support the hypothesis that the
red blood cell itself serves a role in determining O(2) supply to tissue.
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Abstracts