Osmotic reflection coefficients of canine subcutaneous adipose tissue endothelium

Abstract

Volume changes were produced in isolated perfused canine subcutaneous adipose tissue when hydrophilic solutes were added to the perfusate. The initial volume slopes per unit osmolality change yielded the following product: (observed reflection coefficient × filtration coefficient) for the endothelial barrier. The filtration coefficient (CFC), determined from the sustained constant volume change per increment of venous pressure, averaged 0.027 ml × min −1 × 100 g −1. The observed reflection coefficients were (mean ± SE): sodium chloride, 0.0227 ± 0.002; sucrose, 0.0333 ± 0.003; raffinose, 0.0340 ± 0.002; and Ficoll 70, 0.9110 ± 0.160. The relatively high capacity for filtration of adipose tissue capillaries (compared with those in skeletal muscle) was confirmed. The observed reflection coefficients for exchange vessels in fat were about one tenth of the values reported for lung, cardiac, and skeletal muscle endothelium.