Periodic pattern of pancreatic secretory proteins - a call for revision of 'parallel/nonparallel secretory' hypotheses

V. Lesniewska, T. Ploszaj, W. Barej, R. Zabielski
1999 Reproduction nutrition development (Print)  
A great number of studies on pancreatic secretory responses to food and food components (protein, fat) and neurohormonal secretagogues (e.g. acetylcholine, CCK) have been addressed to solve the problem of parallel versus nonparallel secretion of pancreatic juice proteins. Apparently opposite findings were reported (Liebow, Pancreas 3 (1988) 343-351) possibly due to an ill-defined 'basal' secretion of pancreatic proteins (which was a reference for stimulated secretion). Moreover, since the
more » ... er, since the original studies by Boldyreff on conscious dogs (Boldyreff, Ergebn Physiol. 11 (1911) 121-217) it has been known that in fasting conditions the exocrine pancreas secretes juice in a cyclical pattern that is synchronised with the changes in small intestinal motility. The periodic pattern of pancreatic juice secretion (PPS) associated with the duodenal migrating motor complex (MMC) was later demonstrated in other species including humans (Vantrappen et al., Scand. ability in the composition of pancreatic juice proteins is still questionable. The aim of this study was to check to what extent the overall composition of pancreatic juice proteins depends on physiological fluctuations in the secretion of pancreatic juice. The present study was performed on five neonatal calves (2 weeks old) with chronically implanted duodenal serosal electrodes, pancreatic duct catheter and duodenal cannulas. Sampling of pancreatic juice started 1 week after surgery. Samples of pure, pancreatic juice were collected in the trough at the peak of preprandial PPS/MMC cycles. Duodenal electromyogram (emg) recordings enabled precise identification of MMC phases and their PPS-related cycles. The distribution of secretory proteins in pancreatic juice samples was determined by an SDS-PAGE electrophoresis automated system, scanning and protein band density analysis. In all the examined calves the interdigestive pancreatic secretion fluctuated periodically in phase with the duodenal MMCs. The lowest rate of juice secretion (volume and protein output) was observed during phase I of the duodenal MMC. The juice secretion increased during the early phase II, and the peak was observed during the late phase II of the duodenal MMC. The number of electrophoretically detectable proteins varied according to the phase of the PPS cycle; there were 21 bands detected during the secretory peak (i.e. late phase II of the MMC) and 17 bands were detected during the secretory trough of the PPS (i.e. phase I of the MMC). The number of detectable bands during feeding (cephalic phase) was decreased to 15 bands. Moreover, within the detectable bands there were significant differences in the trace density (band optical density x band height) between the peak and the trough of the PPS cycle. In conclusion, the present results
doi:10.1051/rnd:19990105 fatcat:vieyplk4yrdsldd5ghtcvv3u74