Adenosine handling in interstitia of cremaster muscle studied by bioassay
Mohrman, D.E.
American Journal of Physiology 254(2 Pt 2): H369-H376
1988
ISSN/ISBN: 0002-9513 PMID: 3344827 Document Number: 312153
We used video-microscopic techniques to study responses of rat cremaster muscle arterioles to adenosine (ADO) placed in a bathing solution in an effort to determine 1) the sensitivity of these vessels to local interstitial ADO concentration and 2) the parameters of interstitial adenosine handling. Two vessels, located at different depths (.apprxeq. 40 and 115 .mu.m) below the surface of the tissue, were studied simultaneously. Invariably, a higher bath ADO concentration were required to induce vasodilation in the deeper vessel; the concentration required for 50% dilation response (EC50) for ADO dilation increased at an average of 1.8 .+-. 0.2 log10 U/100 .mu.m of depth into the tissue. This result was shown to be due to a standing gradient in interstitial ADO concentration. By extrapolating results to the tissue surface, we estimate that the EC50 for arteriolar dilation to local interstitial ADO is .apprx. 0.1 .mu.M. The steepness of the tissue ADO gradient indicates that the rate constant for interstitial ADO loss is near 0.24/s. The gradient for nonmetabolizable adenosine analogues were < 1/10th as steep as that for ADO itself. Qualitatively similar results were obtained from experiments on hamster cremaster muscle preparations.