Contribution of red blood cell aggregation to venous vascular resistance in skeletal muscle
Cabel, M.; Meiselman, H.J.; Popel, A.S.; Johnson, P.C.
American Journal of Physiology 272(2 Pt 2): H1020-H1032
1997
ISSN/ISBN: 0002-9513 PMID: 9124410 Document Number: 483056
The effects of red blood cell aggregation on venous vascular resistance and conductance were examined in the cat lateral gastrocnemius muscle. During perfusion with blood of normal hematocrit, venous conductance fell linearly by 41% when blood flow was reduced from 5 to 1 ml cntdot min-1 cntdot 100 g tissue-1 and increased linearly by 155% when flow was increased from 5 to 20 ml cntdot min-1 cntdot 100 g tissue-1. This effect was not seen when the muscle was perfused with an acellular solution of 12% Dextran 40 in Ringer solution and was greatly reduced or absent with a nonaggregating suspension of red blood cells in Ringer solution + Dextran 40. Also, the venous vascular conductance at a control flow of 5 ml cntdot min-1 cntdot 100 g tissue-1 during perfusion with the nonaggregating red blood cell suspension was twice that with normal blood of the same hematocrit. The effect of flow on venous conductance was significantly reduced when red blood cell aggregation was increased by addition of Dextran 250 to the blood (200 mg/kg body wt) and was also reduced in animals with systemic hematocrit gt 50%. These findings suggest that red blood cell aggregation contributes importantly to venous vascular resistance in resting muscle.