CHANGES IN ELEMENT CONCENTRATIONS INDUCED BY AGONIST IN PIG PANCREATIC ACINAR-CELLS

Changes in electrolytes of pig pancreatic acinar cells following appli cation of gastrin-cholecystokinin (CCK) were investigated using the te chnique of X-ray microanalysis of hydrated and dehydrated sections of freshly frozen pancreas. After stimulation by CCK (10(-9) M), Na and C l increased significantly in the cytoplasm [Na, from 10 mmol/kg wet st . (48 mmol/kg dry wt.) to 19 mmol/kg (95 mmol/kg); Cl, from 22 mmol/kg (105 mmol/kg) to 49 mmol/kg (245 mmol/kg)] as well as in the luminal interspace [Na, from 53 mmol/kg (189 mmol/kg) to 65 mmol/kg (283 mmol/ kg); Cl, from 65 mmol/kg (232 mmol/kg) to 102 mmol/kg (443 mmol/kg)]. In the secretory granules Cl increased significantly from 30 mmol/kg ( 86 mmol/kg) to 67 mmol/kg (203 mmol/kg). K decreased significantly fro m 120 mmol/kg (571 mmol/kg) to 81 mmol/kg (405 mmol/kg) in the cytopla sm, while both increased from 38 mmol/kg (109 mmol/kg) to 58 mmol/kg ( 176 mmol/kg) in the granules and from 46 mmol/kg (164 mmol/kg) to 48 m mol/kg (209 mmol/kg) in the luminal interspace. Ca increased significa ntly in the cytoplasm as well as in the luminal interspace, and decrea sed significantly in the secretory granules. CCK evoked Ca release fro m secretory granules in the secretory pole of acinar cells. The values were measured from dehydrated sections, and agreed well with those fr om hydrated sections. The effect of furosemide, an inhibitor of the Na +-K+-2Cl(-) co-transporter, on the ion transport of acinar cell was st udied. When furosemide (10(-5) M) was added to the external solution, the cytoplasmic Cl and Ca concentrations decreased significantly, whil e there was a little decrease in Na and K concentrations under the sec retory condition. These results indicate that Na+-K+-2Cl(-) co-transpo rt, and Na+, Cl- and K+ exits into the lumen are involved in the mecha nism of ion secretion in pig pancreatic acinar cells.