Molecular aspects of membrane stabilization by ursodeoxycholate [see comment]

Area of Science:

• Hepatobiliary Science
• Membrane Biophysics
• Pharmacology

Background:

• Ursodeoxycholate (UDC) is a therapeutic agent for biliary liver diseases.
• UDC demonstrates protective effects against bile salt-induced membrane damage in experimental models.
• Hepatocyte and red blood cell membranes were utilized to investigate UDC's protective mechanisms.

Purpose of the Study:

• To investigate the protective effect of ursodeoxycholate against chenodeoxycholate-induced membrane damage.
• To elucidate the mechanism by which ursodeoxycholate stabilizes cell membranes.

Main Methods:

• Incubation of isolated red blood cell and hepatocyte membranes with chenodeoxycholate and ursodeoxycholate.
• Assessment of membrane structural changes using electron paramagnetic resonance spectroscopy and spin labels.
• Analysis of membrane lipids and 14C-labeled bile acids to confirm findings.

Main Results:

• Chenodeoxycholate induced membrane damage by increasing polarity and solubilizing lipids.
• Preincubation with ursodeoxycholate or its conjugates prevented chenodeoxycholate-induced membrane damage.
• Ursodeoxycholate bound to the apolar domain, while its conjugates bound to the membrane interface.

Conclusions:

• Ursodeoxycholate and its conjugates stabilize membrane structure by binding to specific membrane domains.
• This binding prevents chenodeoxycholate-induced lipid solubilization and subsequent water permeation.
• The findings support ursodeoxycholate's therapeutic role in biliary liver diseases by maintaining membrane integrity.