The secretion of alkali metal ions by the perfused cat pancreas as influenced by the composition and osmolality of the external environment and by inhibitors of metabolism and Na⁺, K⁺‐ATPase activity

Abstract

SUMMARY1. The secretion of sodium, potassium and lithium has been studied in the isolated cat pancreas, perfused with bicarbonate buffered saline solutions of varying composition and osmolality, and stimulated maximally with secretin.2. Under isosmolal conditions, when perfusate sodium chloride was replaced by sucrose, sodium secretion and potassium secretion were directly related to perfusate sodium concentration, [Na] The concentration of potassium in the secretion was almost identical with that in the perfusate over the whole concentration range.6. Replacement of perfusate sodium by lithium reduced the volume of secretion, though a small secretion was maintained even in the complete absence of sodium. The concentration of lithium in the secretion was generally slightly greater than that in the perfusate.7. Omission of potassium from the perfusate reduced secretion by about 65 %. Rubidium was a complete substitute for potassium; caesium was not.

Lacrimal gland electrolyte and water secretion in the rabbit: localization and role of (Na+ + K+)‐activated ATPase.

“…First, in the present study, ACh-induced secretion of lacrimal gland fluid was inhibited by ouabain, suggesting that the (Na+ + K+)-activated ATPase does play a role in lacrimal gland fluid secretion. This result is in agreement with another study on the lacrimnal gland (Botelho & Fuenmayor, 1981), in which 5 x 10-6 M-ouabain irreversibly inhibited secretion, and with studies on other exocrine glands including the submandibular glands (Petersen & Poulsen, 1967), sweat glands (Sato et al 1969), and pancreas (Case & Scratcherd, 1974).…”

“…Thus, ouabain, a specific inhibitor of (Na+ + K+)-activated ATPase, has been shown to inhibit exocrine gland fluid secretion (Petersen & Poulsen, 1967;Sato, Taylor & Dobson, 1969;Case & Scratcherd, 1974). Since Na+ is the dominant cation in most exocrine secretions, the simplest mechanism by which the (Na+ + K+)-activated ATPase could play a role in secretion would be by actively transporting Na+ from the secretary cells into the glandular lumen.…”

Localization of sodium pump sites in cat pancreas.

“…The very high density of silver grains over the basolateral plasma membranes of the duct cells, combined with the established ouabain sensitivity of pancreatic electrolyte and water secretion (Ridderstap & Bonting, 1969;Case & Scratcherd, 1974), lends strong support to the view that the cells of the duct system play an important role in electrolyte and water secretion. It has previously been demonstrated by micropuncture studies (Schulz, Yamagata & Weske, 1969;Swanson & Solomon, 1973) that the interlobular ducts contribute to pancreatic secretion of electrolytes and water in the rabbit.…”

“…The detailed mechanisms of pancreatic secretion ofelectrolytes and water are not very well understood. However, a number of important observations have been made, among which is that ouabain, a specific inhibitor of the (Na+ + K+)-activated ATPase (Glynn, 1964;Skou, 1965), is able to inhibit the secretion of pancreatic juice (Ridderstap & Bonting, 1969;Case & Scratcherd, 1974). Therefore, it can be concluded that the cells which are involved in pancreatic secretion of electrolytes and water must be able to bind [3H]ouabain, and probably to a greater extent than other pancreatic cells.…”

“…Such a role would require the (Na+ + K+)-activated ATPase to be located on the luminal plasma membrane of the secretary cells. It must be pointed out that such a location cannot be ruled out by the observation that intravascularly administered ouabain can block pancreatic secretion (Ridderstrap, & Bonting, 1969;Case & Scratcherd, 1974). The pancreatic epithelium is quite leaky (Dewhurst, Hadi, Hutson & Scratcherd, 1978;Jansen, De Pont & Bonting, 1979;Jansen, 1980), and it has been demonstrated that ouabain is able to cross the epithelium of salivary glands (Bundgaard, Moller & Poulsen, 1977).…”