The electrical properties of resting and secreting pancreas

1. The electrical properties of the resting and stimulated pancreas have been studied in the anaesthetized cat. There is an inverse relationship between the frequency of applied alternating current and the resistivity and dielectric constant of the resting pancreas. The resistivity is also affected by the fat content of the gland. The impedance locus of the pancreas is similar to that of other tissues.2. On intravenous injection of secretin there is a brief increase, followed by a more marked decrease, in conductance and capacitance of the pancreas. The phase of decreased conductance is related to the flow of pancreatic juice. The decrease in conductance and the flow rate can be characterized by two closely related empirical equations.3. During secretin stimulation the sodium concentration in pancreatic tissue increases, and the potassium concentration falls.4. It is tentatively suggested that the decreased conductance across the secreting gland is mostly due to swelling of the secretory cells and to a minor degree is the result of changes in the composition of the secretion in the pancreatic ducts.5. In the anaesthetized cat the mean half life of the secretory action of secretin is 199 sec.

On the histochemistry of azo group-free thiazole dyes

Analysis of primuline, thioflavine S and thioflavine T acid and basic azo group-free thiazole dyes showed that they were built up from a number of components which were characterized by physicochemical methods. It was found that the isolated components, as well as related substances of known chemical composition, have characteristic staining properties. Factors involved in the staining mechanism of the dyes and of components—dye concentration, pH, aggregation of the dye molecules—were investigated and their roles are discussed. Selectivity of these fluorescent staining methods was also studied.