AJP - Heart and Circulatory Physiology, Vol 250, Issue 3 482-H489, Copyright © 1986 by American Physiological Society
Endothelial cell uptake of adenosine in canine skeletal muscle
M. W. Gorman, J. B. Bassingthwaighte, R. A. Olsson and H. V. Sparks
The vascularly isolated muscles in the hindlimbs of five dogs were perfused
with an oxygenated physiological salt solution. The extractions of
adenosine and of a nontransported analogue of adenosine,
9-beta-D-arabinofuranosyl hypoxanthine (AraH), were determined by the
single-pass indicator-dilution technique. A bolus containing [125I]albumin
(reference tracer), [14C]adenosine, and [3H]AraH was injected into the
artery while samples of venous effluent were collected over the next
minute. This injection was repeated with dipyridamole (10(-5) M) in the
perfusate. Early extractions of AraH (EAra) and adenosine (EAdo) under
control conditions were 48 +/- 4 and 80 +/- 4%, respectively. In the
presence of dipyridamole, EAra was unchanged (47 +/- 5) while EAdo
decreased to 45 +/- 7%. Since early extraction reflects primarily the
barrier posed by endothelial cells, these results demonstrate significant
endothelial uptake of adenosine. Analysis of these data using a
mathematical model of blood-tissue exchange indicates that, under the
conditions of these experiments, at least 78% of the adenosine taken up by
skeletal muscle entered endothelial cells.
