ALTERATION IN THE FLUORESCENCE POLARIZATION OF RAT PLASMA AND LIVER-CELL MEMBRANES FOLLOWING BILE-DUCT LIGATION IN RATS

The fluorescence polarization levels of liver cell membranes and plasm a were analyzed to determine membrane fluidity following bile duct lig ation (BDL) in rats. Fluorescence polarization was measured with a spe ctrofluorophotometer equipped with polarizers, using 1,6-diphenyl-1,3, 5-hexatrien (DPH) as a probe. After bile duct ligation, liver cell mem brane fluidity decreased significantly for up to 14 days after surgery (P < 0.001 on 3rd and 7th days). The polarization of the plasma in ra ts with BDL slightly but significantly increased compared to the level s in the control animals over the 14-day period following BDL. In addi tion, a small but significant correlation in the polarization levels b etween plasma and liver cell membranes (r = 0.362, P < 0.02) was obser ved. The co-incubation of BDL plasma with normal liver cell membranes resulted in a decrease in membrane fluidity, which suggested that BDL rat plasma had a direct effect on membrane fluidity. After a 70% hepat ectomy, the polarization of the membranes from remnant livers in the B DL rats remained elevated relative to the sham-operated controls. It i s thus concluded that the membrane fluidity of the livers in BI)L rats decreases following bile duct ligation and does not increase after a 70% hepatectomy, presumably due to the increased plasma level of bilir ubin.