Ethanol impairs calcium homeostasis following CCK-8 stimulation in mouse pancreatic acinar cells

Abstract

Alcohol consumption has long been associated with cell damage, and it is thought that it is involved in approximately 40% of cases of acute pancreatitis. In the present study, we have investigated the early effects of acute ethanol exposure on cholecystokinin octapeptide (CCK-8)-evoked calcium (Ca 2+) signals in mouse pancreatic acinar cells. Cells were loaded with fura-2 and the changes in fluorescence were monitorized using a spectrofluorimeter. Our results show that stimulation of cells with 1 nM CCK-8 led to a transient increase in [Ca 2+] c, which consisted of an initial increase followed by a decrease of [Ca 2+] c toward a value close to the prestimulation level. In the presence of 50 mM ethanol, CCK-8 lead to a greater Ca 2+ mobilization compared to that obtained with CCK-8 alone. The peak of CCK-8-evoked Ca 2+ response, the “steady-state level” reached 5 min after stimulation, the rate of decay of [Ca 2+] c toward basal values and the total Ca 2+ mobilization were significantly affected by ethanol pretreatment. Thapsigargin (Tps) induced an increase in [Ca 2+] c due to its release from intracellular stores. After stimulation of cells with CCK-8 or Tps in the presence of 50 mM ethanol, a greater [Ca 2+] c peak response, a slower rate of decay of [Ca 2+] c, and higher values of [Ca 2+] c were observed. The effects of ethanol might result from a delayed or reduced Ca 2+ extrusion from the cytosol toward the extracellular space by plasma membrane Ca 2+adenosine triphosphatase (ATPase), or into the cytosolic stores by the sarcoendoplasmic reticulum Ca 2+-ATPase. Participation of mitochondria in Ca 2+ handling is also demonstrated. The actions of ethanol on CCK-8 stimulation of cells create a situation potentially leading to Ca 2+ overload, which is a common pathological precursor that mediates pancreatitis.