Pancreatic tissue oxygenation during secretory stimulation.

Pancreatic acinar tissue O2 tension (PO2) was measured in anesthetized rats using recessed-tip microelectrodes (tip diam 1-2 micron). Pancreatic blood flow was measured using radioactive microspheres. Volume rate of pancreatic secretion, as well as protein concentration, was also measured. Average resting PO2 was 24.8 +/- 1.6 mmHg, with relatively little variation evident within a given pancreas. Bolus intravenous infusion of cholecystokinin octapeptide (CCK-OP, 4 micrograms X kg body wt-1) induced a reduction in tissue PO2 and profoundly increased protein output, while not directly affecting pancreatic blood flow. By contrast, secretin infusion (1.0 CU X kg body wt-1 iv bolus) affected neither tissue PO2 nor blood flow, although secretory rate increased by nearly sevenfold. This difference in PO2 response to the two compounds is interpreted in light of the fact that CCK-OP primarily stimulates acinar cell function, while secretin preferentially activates secretory epithelium. Pancreatic PO2 was found to be linearly related to resting blood flow at flows above 44 ml X min-1 X 100 g-1. No regional differences in blood flow were found in the head, body, and tail of the pancreas.