Increased calcium influx in the presence of ethanol in mouse pancreatic acinar cells

Abstract

The effects of alcohol on Ca(2+) signalling remains poorly understood. Here we have investigated the effects of acute ethanol exposure on Ca(2+) influx in mouse pancreatic acinar cells. Cells were loaded with fura-2 and the changes in fluorescence were monitored by spectrofluorimetry and imaging analysis. Stimulation of cells with 20 pM cholecystokinin evoked an oscillatory pattern in [Ca(2+)](c), both in the presence and in the absence of extracellular Ca(2+). Stimulation of cells with cholecystokinin in the presence of 50 mM ethanol led to a transformation of physiological oscillations into a single transient increase in [Ca(2+)](c). This effect was observed when Ca(2+) was present in the extracellular medium, and did not appear in its absence. Addition of 1 mM CaCl(2) to the extracellular medium, following release of Ca(2+) from intracellular stores by stimulation of cells with 1 nM cholecystokinin or 1 microM thapsigargin in the absence of extracellular Ca(2+), was followed by an increase in [Ca(2+)](c). Ca(2+) influx was increased in the presence of 50 mM ethanol. The anti-oxidant cinnamtannin B-1 (10 microM) or inhibition of alcohol dehydrogenase by 4-MP (1 mM), significantly reduced Ca(2+) influx evoked by cholecystokinin in the presence of ethanol. In summary, intoxicating concentrations of ethanol may lead to over stimulation of pancreatic acinar cells by cholecystokinin. This might be partially explained by the generation of reactive oxygen species and an increased Ca(2+) entry in the presence of ethanol. Potentially ethanol might lead to Ca(2+) overload, which is a common pathological precursor that is implicated in pancreatitis.

Molecular and cellular mechanisms of pancreatic injury

“…Del Castillo-Vaquero et al . [9] showed that acute application of ethanol at clinically relevant concentrations (1–50 mmol/l) to isolated acinar cells resulted in Ca 2+ influx due to the production of oxidative metabolites of alcohol. Together, the studies implicate a role for alcohol metabolites in acinar cell injury through aberrant Ca 2+ signals.…”

Raf-1 Kinase Inhibitory Protein (RKIP) Mediates Ethanol-induced Sensitization of Secretagogue Signaling in Pancreatic Acinar Cells

“…Although alcohol abuse has been long recognized as a risk factor for acute and chronic pancreatitis, the molecular mechanism mediating the sensitizing affect of EtOH on secretagogue signaling in acinar cells has remained largely unresolved (26,27). In this study we show that RKIP is a substrate for EtOHinduced PKC-dependent phosphorylation and a critical mediator of EtOH-induced sensitization of secretagogue signaling.…”

“…Exposing either experimental animals or isolated pancreatic acinar cells to EtOH sensitizes the cells to physiologic secretagogue stimulation (22)(23)(24)(25)(26) and deregulates normal agonist-in-duced Ca 2ϩ responses and zymogen activation (27,28). Specifically, it has been shown that after treatment of isolated pancreatic acinar cells either with EtOH or its non-oxidative metabolites, physiological concentrations of secretagogue induces sustained increases in [Ca 2ϩ ] cyto that are no longer limited to the apical pole but spread throughout the acinar cell (28,29).…”

Mechanisms of alcoholic pancreatitis

“…A recent study by Castillo‐Vaquero et al 61 . suggests an additional source for raised intracellular calcium in alcohol‐exposed acinar cells.…”