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Bile acid accumulation in gastric mucosal cells
S Batzri1, J W Harmon, E J Schweitzer
1Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799.
This study examined how bile acids interact with gastric mucosal cells. Researchers found that bile acids like glycocholic acid rapidly accumulate in these cells, reaching concentrations up to eight times higher than in the surrounding fluid. The process is pH-dependent, with more accumulation at acidic pH. The accumulation does not require energy and is not species-specific. Experiments showed that about half of the bile acid is stored in the cytoplasm and half in membranes. These findings suggest that bile acids can damage the stomach lining even at low concentrations due to intracellular entrapment and membrane binding.
Area of Science:
- Gastrointestinal physiology
- Cellular toxicology
- Bile acid metabolism
Background:
Bile acids are known to disrupt the gastric mucosal barrier, but the exact mechanism remains unclear. While prior research has shown that bile acids can solubilize mucosal lipids, the role of cellular uptake is less understood. This gap motivated the need to explore how bile acids interact with gastric mucosal cells. No prior work had resolved whether bile acid entry into cells is a key step in injury. The study aimed to address this uncertainty by examining bile acid-cell interactions. The field lacks detailed data on how low concentrations of bile acids can still cause damage. Researchers have not yet confirmed if this process is energy-dependent or species-specific. Understanding these factors could clarify the pathophysiology of bile acid-induced injury.
Purpose Of The Study:
The study aimed to investigate how bile acids interact with gastric mucosal cells. It sought to determine if bile acids enter cells and how this process occurs. Researchers focused on glycocholic and deoxycholic acids in rabbit and guinea pig models. The goal was to assess whether cellular uptake is a key step in mucosal injury. The study also aimed to identify the conditions under which accumulation occurs. Researchers wanted to test if the process is energy-dependent or pH-sensitive. They aimed to clarify whether the mechanism is conserved across species. This work could help explain how low bile acid concentrations still cause damage.
Main Methods:
The study used dispersed gastric mucosal cells from rabbit and guinea pig stomachs. Researchers tested glycocholic and deoxycholic acid interactions with these cells. They measured bile acid concentrations in cells over time. Steady-state concentrations were reached within 30 minutes. The experiments varied pH levels to assess their effect on accumulation. Cellular energy dependence was tested using metabolic inhibitors. Cytoplasmic and membrane associations were studied using 86Rb as a marker. The process was evaluated for species specificity by comparing rabbit and guinea pig cells.
Main Results:
Glycocholic and deoxycholic acids rapidly associated with gastric cells. Glycocholic acid reached eight times the concentration in the medium. Accumulation was higher at acidic pH than at neutral pH. The process was not energy-dependent and did not saturate. Bile acid binding was consistent across species tested. Cytoplasmic and membrane compartments both retained bile acids. Approximately half of glycocholic acid was in the cytoplasm. The rest was associated with cellular membranes. These findings suggest entrapment and binding as accumulation mechanisms.
Conclusions:
The study suggests that bile acids accumulate in gastric cells via entrapment and membrane binding. Accumulation occurs rapidly and reaches steady state within 30 minutes. The process is pH-dependent and does not require cellular energy. The findings are consistent across species tested. Bile acid accumulation may explain how low luminal concentrations cause damage. Cytoplasmic and membrane compartments both store bile acids. This mechanism could underlie the pathogenesis of mucosal injury. The study supports the idea that intracellular ionization and binding are key.
Frequently Asked Questions
Bile acids accumulate via entrapment and binding to cytoplasmic and membrane compartments. Glycocholic acid reached eight times the medium concentration.
Accumulation is pH-dependent, with higher uptake at acidic pH. It is not energy-dependent and does not saturate.
Acidic pH increases accumulation, suggesting intracellular ionization traps bile acids in the cytoplasm.
Membrane binding contributes to accumulation, with half of glycocholic acid found in membranes.
The process is not species-specific, as seen in both rabbit and guinea pig cells.
Accumulation may explain how low luminal concentrations cause mucosal injury through entrapment and binding.