The secretion of electrolytes and enzymes by the pancreas of the anaesthetized cat

Abstract

1. The bicarbonate concentration in cat pancreatic juice falls and the chloride concentration increases at slow secretory rates. The concentration of sodium and potassium remain constant at all secretory rates.2. Acetazolamide reduces the maximal rate of secretion markedly, and the maximal bicarbonate concentration slightly, but does not alter the reciprocal relationship between bicarbonate and chloride at slow rates of flow.3. By perfusion of the main duct it has been shown that there is a loss of bicarbonate and a gain of chloride across the duct wall due to a passive process of exchange diffusion. It is suggested that this may account for a substantial part of the flow-dependent changes in bicarbonate and chloride concentrations in the intact gland.4. The enzyme content of pancreatic juice is made up of a small continuous basal output, to which may be added a much larger secretion in response to hormonal stimulation.5. From analysis of successive small samples of juice it has been found that the response to single injections of pancreozymin lasts a very short time, during which the secretory cells release enzymes in a small volume of chloride-containing fluid.6. It is concluded that in the cat pancreatic secretion consists of an isosmolar primary secretion mostly of sodium bicarbonate, to which is added small amounts of a chloride-containing enzyme secretion. This fluid is modified, particularly at slow flow rates, by transductal exchange of chloride and bicarbonate which, at least in the main duct, is passive in nature.

Prostaglandin action on pancreatic blood flow and on electrolyte and enzyme secretion by exocrine pancreas in vivo and in vitro

“…When electrolyte and water secretion is stimulated from a previously resting cat pancreas (in vivo or in vitro), the secretion is rich in enzymes, whether the stimulus is secretin (Case, Harper & Scratcherd, 1969), dibutyryl cyclic AMP or theophylline , or prostaglandins . This so called 'wash-out' phenomenon results from a small but continuous basal secretion of enzymes into the duct system and is therefore a passive secretion; it cannot be used as evidence that any of these stimuli, including prostaglandins, actively stimulate enzyme secretion by the gland.…”

Secretion of calcium in pancreatic juice.

“…This conclusion is based on the observation that both the concentration of calcium and the kinetics of 45Ca secretion are completely different in the pancreatic juice elicited by the injection of either secretin or caerulein, i.e. in two experimental conditions characterized by the stimulation of either one of the cellular systems of the exocrine pancreas: the acinar and the duct cells (Case, Harper & Scratcherd, 1969;Case, 1973a, b). It should be emphasized that, according to our results, in neither one of these conditions is the secretion of calcium in the pancreatic juice due exclusively to one of the two possible sources.…”

Fluid secretion and electrical properties of pancreatic acini of Syrian Golden hamster.

“…Thus, in the hamster pancreas the acinar cell stimulants evoke a smaller fluid secretion than in the mouse or rat pancreas. It is concluded that the function of the hamster pancreatic acini in fluid secretion is rather similar to that of the cat (Case et al 1969) and man (Rinderknecht et al 1978) than to that of the mouse and the rat.…”

“…Species can be classified into two groups with respect to the degree of fluid secretion ; the first group includes the rat (Petersen and Ueda 1977) and mouse (Mangos et al 1973) in which the pancreas secretes enzymes together with a large amount of pancreatic juice, and the second group includes the cat (Case et al 1969) and man (Rinderknecht et al 1978) in which the pancrease secretes enzyme with little juice.…”