Perifusion of isolated rat pancreatic acini: carbamylcholine-induced biphasic amylase release.

To solve many problems in other in-vitro methods such as perfusion and static incubation, perifusion of isolated rat pancreatic acini was established. Continuous stimulation by carbamylcholine induced a biphasic secretory response, a sharp initial phase and a slow-varying second phase. The junction of these two phases occurred at almost the same time (in about 7 min of stimulation) at any concentration of carbamylcholine. The slow-rising former part of a second phase indicated that a biphasic pattern is produced by overlapping of two kinds of real phases and the beginning of a real second phase occurs at the time of the junction. The concentration dependence of amylase release showed a bell-shaped pattern and the maximal amylase release at an optimal concentration (10(-6)M) was 5.43 +/- 0.24% total/30 min. The sustained latter part of a second phase showed a slow decline at optimal or less concentrations but a plateau at supraoptimal concentrations.