Résumé : (1) Rat pancreas fragments were perfused for 2hr with Krebs-Ringer bicarbonate buffer enriched with 10 mM glucose and Trasylol (500 UIK/ml). Amylase output was estimated at 5-min intervals on successive samples of the effluent. (2) Pancreozymin at a concentration of 7.10-9 M doubled amylase output when introduced after 1 hr of preincubation. Administration of 10 mM NaF promoted a biphasic effect. The initial and transient hypersecretory peak was followed by a second and more prolonged period of hypersecretion. It is assumed that the primary component of the biphasic response was due to hyperosmolarity, and it is tentatively suggested that the secondary response to NaF was the result of variations in the phosphorylation of membrane proteins. (3) Paired tissue fragments were pre-exposed for 30 min to digitonin, sodium dodecylsulfate, Triton X-100, or bovine trypsin (the proteolytic enzyme in the absence of Trasylol). The basal output of amylase rose with increasing detergent concentrations (from 100 to 500 μg/ml but not after trypsin pretreatment. The four agents were equally effective in reducing the sensitivity to pancreozymin. They did not impair the initial osmotic response to NaF, but did curtail the prolonged second NaF hypersecretory effect. Digitonin and dodecylsulfate were less effective in this respect than either Triton X-100 or trypsin though being equally detrimental to pancreozymin action. (4) These observations suggest that the regulation in vitro of secretion by pancreozymin and NaF in intact acinar cells of the rat pancreas involves two distinct loci of a membrane-lipoprotein complex. © 1975.