Caffeine is contained in coffee, tea, and numerous beverages and foods. We examined the direct effects of caffeine on the physiological function of pancreatic duct cells by using interlobular duct segments isolated from guinea pig pancreas.Methods
The rate of fluid secretion was continuously measured by monitoring the luminal volume of isolated duct segments. Changes in intracellular Ca2+ concentration ([Ca2+]i) were estimated by microfluorometry in ducts loaded with Fura-2.Results
Both secretin-stimulated and acetylcholine (ACh)-stimulated fluid secretions were substantially and reversibly inhibited by relatively low concentrations of caffeine as low as 0.03 mM relevant to blood levels after ingestion of caffeine-containing beverages. Caffeine inhibited ACh-induced elevation of [Ca2+]i and secretin-induced fluctuation of [Ca2+]i. Caffeine abolished thapsigargin-induced intracellular Ca2+ release but did not affect the entry of extracellular Ca2+. Caffeine (0.05 mM) abolished ethanol (1 mM)-induced fluid hypersecretion in secretin-stimulated pancreatic duct.Conclusions
Low concentrations of caffeine directly inhibit pancreatic ductal fluid secretion stimulated by secretin or ACh and also ethanol-induced fluid hypersecretion. The inhibition by caffeine seems to be mediated by the blockade of intracellular Ca2+ mobilization. Daily intake of caffeine may reduce the volume of pancreatic juice secretion.