Pyruvate and Glutamine Define the Effects of Cholecystokinin and Ethanol on Mitochondrial Oxidation, Necrosis, and Morphology of Rat Pancreatic Acini.

ABSTRACT

OBJECTIVES: The objective of this study was to test whether pyruvate and glutamine affect the ethanol and cholecystokinin (CCK) effects on the mitochondrial function, viability, and morphology of rat pancreatic acini. METHODS: Respiration was measured with Clark oxygen electrode. Mitochondrial membrane potential, reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H), cell morphology, and viability were studied with fluorescence microscopy. RESULTS: In vitro, CCK (0.1 nM) caused pyruvate-dependent stimulation of basal and uncoupled respiration, and the effects were abolished by ethanol (20 mM). The combination of ethanol with CCK (2 hours) caused necrosis of approximately 40% acinar cells in medium with glucose, but not with pyruvate and/or glutamine. Cholecystokinin (10 nM) or ethanol with 0.1 nM CCK caused plasma membrane blebbing not related to apoptosis only when both glutamine and pyruvate were present. Glutamine, but not pyruvate, decreased NAD(P)H level and prevented the effects of ethanol with CCK on mitochondrial membrane potential and NAD(P)H, but, in combination with CCK and ethanol, decreased the uncoupled respiration. In vivo, the combination of ethanol (4 g/kg) and CCK (20 pmol/kg) suppressed basal and uncoupled respiration and caused acinar cell blebbing, but not necrosis. CONCLUSIONS: The lack of sufficient substrate supply in vitro makes pancreatic acinar cells susceptible to necrosis caused by ethanol and CCK in clinically relevant concentrations.