The effects of cholecystokinin-pancreozymin, acetylcholine and secretin on the membrane potentials of mouse pancreatic cells in vitro.

Cell membrane potentials in an in vitro preparation of mouse pancreas have been measured and the effects of cholecystokinin-pancreozymin, acetylcholine and secretin studied. The membrane potential-frequency histogram has four distinct peaks and was split into the sum of four Gaussian distributions with means of minus 14, minus 23, minus 32 and minus 41mV. The minus 32 mV peak is attributed to acinar cells which respond to cholecystokinin-pancreozymin or acetylcholine by depolarising to minus 15 to minus 20 mV, the response lasting up to 10 min. The minus 23 and minus 41 mV peaks are due to duct cells. A duct cell has a resting membrane potential of minus 23 mV and hyperpolarises to minus 41 mV in response to secretin stimulation, the response lasting for longer than 15 min. Duct cells regardless of their position in the duct system function electrophysiologically in identical fashion. The secretory sites for enzyme and electrolyte are distinct, the duct cells secrete only electrolyte while the acinar cells secrete only enzymes.