Electrolyte and inulin spaces of rat salivary glands and pancreas

Abstract

Inulin, sodium, potassium and chloride levels were determined on serum and submaxillary, parotid and pancreatic glands of inulin-administered nephrectomized rats. Methods of tissue preparation and analysis were examined in some detail. From data obtained, volumes of inulin and electrolyte distribution were calculated. Volumes of distribution in submaxillary, parotid and pancreatic glands, in that order, were, for inulin, 198 ml/kg, 257 ml/kg and 209 ml/kg; for sodium, 232 ml/kg, 318 ml/kg and 275 ml/kg; and, for chloride, 365 ml/kg, 460 ml/kg and 388 ml/kg. Comparison of these values led to the conclusion that intracellular sodium in these glands is possible and that intracellular chloride is likely. Intracellular potassium seems present in concentration similar to that in mammalian muscle. From electrolyte data and levels of amylase in parotid gland and its secretion, it is speculated that parotid secretion could be formed from a small fraction (approx. 10%) derived from unmodified intracellular fluid to which is then added solution having electrolyte composition of extracellular fluid. The closely isotonic secretion of rat parotid gland can thus be predicted without assuming appreciable reabsorption of electrolytes or water.