A circulating factor(s) mediates cell depolarization in hemorrhagic shock

Area of Science:

• Physiology
• Biochemistry
• Cell Biology

Background:

• Cellular depolarization is a known consequence of hemorrhagic shock.
• The precise mechanisms driving this depolarization, particularly the role of plasma factors versus hypoperfusion, remain incompletely understood.

Purpose of the Study:

• To investigate the role of plasma factors in inducing cell depolarization during hemorrhagic shock.
• To develop a novel in vitro bioassay for identifying shock-induced plasma mediators of cell depolarization.

Main Methods:

• Utilized a potential-sensitive fluorescent dye (bis-(1,3-dibutylbarbiturioc acid) trimethine oxonal, DIBAC) to measure cell membrane potential.
• Exposed various cell lines and primary cells (e.g., H9C2, A-10, C-9, RBCs, WBCs, HISM) to plasma from rats subjected to hemorrhagic shock.
• Assessed depolarization in relation to plasma concentration, molecular weight of factors (via dialysis), and time of appearance post-shock.

Main Results:

• Plasma from hemorrhagic shock induced cell depolarization across diverse cell types and species.
• Depolarization occurred rapidly (within 5 minutes) and was dependent on plasma concentration, suggesting specific receptor binding.
• The causative factor(s) had a molecular weight greater than 10,000 daltons and were not removed by dialysis.
• Cellular oxygenation was maintained, ruling out hypoperfusion as a necessary condition for depolarization.
• Tumor necrosis factor and platelet-activating factor were not identified as the causative agents.

Conclusions:

• Hemorrhagic shock generates plasma factors that directly cause cell depolarization, independent of hypoperfusion.
• This study establishes a sensitive, noninvasive in vitro bioassay for identifying these critical plasma mediators.
• Further research can elucidate the specific molecular mechanisms and intracellular pathways involved in shock-induced cell depolarization.