Anoxia and capillary filtration coefficient in the isolated cat hindlimb

Isolated cat hindlimbs were perfused from a reservoir with an albumin-blood mixture at a constant flow of 20 ml X min-1 X 100 g muscle-1 while alternately bubbling the perfusate with either 95% O2-5% CO2 gas mixture or a 95% N2-5% CO2 mixture for 50- to 60-min periods. Capillary filtration coefficient (CFC), vascular resistance (R), and perfusate O2 content were measured in each period. The arterial O2 content fell from fully equilibrated to 0.25 vol% during the use of N2. R fell from about 6 mmHg X min X 100 g X ml-1 during O2 bubbling to approximately 1.0 with N2. CFC averaged 0.012 +/- 0.002 ml X min-1 X mmHg-1 X 100 g muscle-1 (SD, n = 6) during the 1st O2 period, rising to 0.016 +/- 0.002 (n = 4) in the 3rd O2 period 4 h later. CFC fell by 5% (P less than 0.001) during the periods of N2 bubbling. Papaverine was present in two experiments without effect on the CFC data. It was concluded that CFC was not meaningfully influenced by vascular resistance or anoxia, a finding that is inconsistent with the concept of local metabolic control of CFC by precapillary resistance vessels.