Figure 2.

Angiopoietin-1 increases continuous microvessel reflection coefficient (s). (A) A single frog mesenteric capillary perfused with 3% bovine serum albumin (BSA), submitted to a series of vessel occlusions made at a variety of luminal hydrostatic pressures (P_c) under baseline conditions (vehicle; open circles), and subsequently following 30-min perfusion with 200 ng mL⁻¹ Angiopoietin-1 (Ang1; closed circles). L_P, the slope of the relation between fluid flux rate per unit vessel area (J_v/A) and P_c was reduced by Ang1, and the x-axis intercept of this relation [triangle: effective oncotic pressure difference (sDp)] was increased. (B) σΔπ was unaltered by 30-min perfusion with vehicle (BSA alone: open circles; squares ± error bars represent mean ± SEM; n = 5 pairs; ^nsP > 0.9, paired t-test). (C) In contrast, 30-min treatment with Ang1 increased σΔπ (and hence σ) in all the 10 vessels studied (*P < 0.001, paired t-test) (squares ± error bars represent mean ± SEM).