Effects of porcine secretin on exocrine and endocrine function in the isolated perfused rat pancreas.

The effects of both synthetic and pure natural porcine secretin on immunoreactive insulin (IRI) and immunoreactive glucagon (IRG) release and on pancreatic exocrine secretion were studied in the isolated perfused rat pancreas. Synthetic porcine secretin stimulated a significant increase in pancreatic juice flow and amylase output at concentrations as low as 0.01 and 0.1 ng/ml, respectively. The maximal peak rate of both juice flow and amylase output was observed at 1 microgram/ml synthetic secretin. Synthetic secretin at concentrations up to 2 micrograms/ml and pure natural porcine secretin at a concentration of 1 clinical unit/ml had no effect on IRI secretion regardless of the glucose concentration (50, 100, or 150 mg/100 ml) in the perfusate. Both types of secretin, however, elicited a concentration-dependent increase in IRG secretion in the presence of 50 mg/100 ml glucose. The lowest synthetic secretin concentration causing a significant increase in IRG release was 0.1 ng/ml, and maximal stimulation was observed at 1 microgram/ml. These concentrations were similar to those eliciting minimal and maximal amylase release. Thus, synthetic and pure natural porcine secretin have been shown to not only stimulate pancreatic juice flow and amylase secretion but also to elicit IRG release from the isolated perfused rat pancreas.