CELL AND OXYGEN FLOW IN ARTERIOLES CONTROLLING CAPILLARY PERFUSION

Measurements of hemodynamic and oxygen transport characteristics in th e arterioles that control capillary perfusion in striated muscle were used to compare oxygen flow into adjacent capillary networks. Observat ions were made in arterioles arising consecutively (branches 1-3 and t he last branch) from a single transverse arteriole. During maximal dil ation [after 5 min of exposure to superfusate with 10(-4) M adenosine (ADO)], mean cell flow into branches decreased significantly with incr easing axial distance along the transverse arteriole, from 8.47 +/- 2. 43 x 10(3) (SE) cells/s in branch 1 to 5.56 +/- 2.14 x 10(3) 3.21 +/- 1.30 x 10(3), and 4.00 +/- 1.33 x 10(3) cells/s in successive branches . During control, cell fluxes were not significantly different by posi tion (2.21 +/- 1.12, 1.31 +/- 0.42, 0.97 +/- 0.31, and 1.23 +/- 0.40 c ells/s in branches 1, 2, and 3 and the last branch, respectively). Bra nch diameters during ADO were not significantly different by position (26.2 +/- 2.9, 24.5 +/- 1.4, 22.0 +/- 2.8, and 26.7 +/- 2.7 mum, respe ctively). Hemoglobin saturations during ADO were not different (59.6 /- 2.2, 60.6 +/- 2.3, 60.3 +/- 2.3, and 61.0 +/- 2.3%, respectively), whereas mean oxygen flow into branch 1 significantly exceeded that int o branches 2 and 3 and the last branch (1.40 +/- 0.40 vs. 0.60 +/- 0.1 7, 0.53 +/- 0.22, and 0.66 +/- 0.22 pl/min, respectively). During cont rol, oxygen flows were not significantly different between branches. T hus, both cell and oxygen flow into these arterioles vary in a systema tic way dependent on their relative branch position; regulatory proces ses serve to make oxygen supply more uniform.