The effects of benzyl alcohol and trypsin on duodenal brush border membranes

Abstract

Duodenal brush border membranes are highly resistant to attack by trypsin: their inherently low membrane fluidity might contribute to this resistance. Treatment of rabbit duodenal brush border membrane vesicles (BBMV) with benzyn alcohol (lo-12omM) produced dose-dependent increases in membrane fluidity and decreases in total enclosed volume (EV), which were correlated (r=0.97). One hour pretreatment of BBMV with benzyn alcohol (10 or 3Om~) increased membrane fluidity from 0.488t 0.013 (n=7) to 0.508+0.004 (n=4) and 0.594t 0.033 (n=5), and decreased EV from 0.75~0.05 pl/mg (n=S) to 0.54tO.06 pl/mg (n=7) or 0.27_+ 0.04 ,ul/mg (n=4) respectively. However, treatment with trypsin (1:lO) for 60 min at 30 C reduced EV by 61.326.3% in control vesicles and by 59.3+11.7% and 40.7216.3% in vesicles treated with benzyl alcohol at 10 and 30 mM respectively (both NSD from control). These data do not support a role for membrane fluidity as a determinant of susceptibility to attack by trypsin