Repeated membrane plasma separation with on-line sorbent treatment of plasma in the conscious rat.

Repeated membrane plasma separation with on-line sorbent treatment of plasma was performed in unrestrained and conscious rats, thus avoiding the possible effects of repeated stress and exposure to anesthetic agents. The procedure was well tolerated, even after four consecutive perfusions. Blood flow was 0.7 ml/min, with a transmembrane pressure of 18.6 mm Hg and plasma filtration rate of 0.21 ml/min. This allowed 12 ml of plasma (greater than 1 plasma volume) to be treated within 1 h. Levels of albumin, immunoglobulin G, and C3 remained constant during each perfusion and were not significantly different from those of animals subjected to control procedures. Results obtained from filtrate were comparable at 15 and 60 min with values obtained from whole blood, with sieving coefficients of approximately 1. Leukocyte, erythrocyte, and thrombocyte counts remained unchanged during each plasma perfusion. A progressive rise in leukocyte counts occurred following successive perfusions, but this was true also of animals subjected to control procedures.