Acinar secretion was studied in the caerulein-stimulated perfused rat pancreas. Unstimulated glands secreted at a mean basal rate of 1.1 microliters X g-1 X min-1 (SD = 0.74), which was not altered by perfusate anion substitution or by transport-blocking drugs. Caerulein evoked a maximum response (6.8 microliter X g-1 X min-1, SE = 0.36, n = 8) at a concentration of 18 pmol/l. Replacement of perfusate bicarbonate with either chloride or acetate did not significantly alter the stimulated secretory rate. In contrast, replacement with acetate of either chloride alone or chloride and bicarbonate reduced the rate of stimulated secretion by 75-80%, and replacement with isethionate abolished the response altogether. In glands perfused with solutions containing chloride but not bicarbonate, furosemide (10(-5) M), 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS, 10(-4) M), amiloride (10(-4) M), and methazolamide (10(-4) M) all reduced the secretory response by more than 70%. When bicarbonate was included in the perfusate, the inhibitory effects for the same doses of blockers were much less, and except for methazolamide the same level of maximum inhibition was obtained when the blocker doses were increased 10-fold. The results suggest that rat pancreatic acini utilize a different secretory mechanism from the sodium chloride-carrying symport postulated to be most important in rat mandibular glands. The simplest model to explain our results would involve paired, basolateral antiports for Na-H and Cl-HCO3 exchange. We cannot exclude the presence of a Na-Cl symport, but if present, its role appears to be minor.

Considerable differences exist among species in the patterns of regulation of pancreatic secretion. Although rabbit pancreas is quite often used for in vivo and in vitro studies of pancreatic function, responses of this gland in vivo to common pancreatic stimuli have never been characterised in detail.That was the purpose of this study. The data demonstrate the existence of a spontaneous fluid secretion that can be increased by intravenous infusions of secretion (sevenfold), cholecystokinin-octapeptide (CCK8) (threefold), and carbachol (sixfold). The electrolyte composition of the secretion evoked by each of these stimuli was similar: sodium and potassium concentrations were constant and slightly higher than those in plasma at all secretory rates, whereas bicarbonate concentration rose with secretory rate to approach a plateau of about 125 mmol/L, and chloride concentration fell to a plateau of about 35 mmol/L. In terms of protein secretion, secretin caused a small but significant rise in output, while CCK8 and carbachol evoked the expected large increase. Thus, regulation of pancreatic electrolyte secretion in rabbit differs from that in dog, cat, and human, on the one hand, and rat, on the other hand, and most closely resembles the pattern observed in guinea pig.

Renal function in women with severe preeclampsia was significantly impaired and highly correlated with systolic or diastolic blood pressure.

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