STUDIES ON ISOLATED SECRETORY GRANULES FROM BOVINE NEUROHYPOPHYSES

• Published in: European journal of endocrinology Vol. 70; no. 4; pp. 625 - 635
• Main Authors: Vilhardt, Hans, Tøndevold, Erik, Larsen, Kirsten
• Format: Journal Article
• Language: English
• Published: 01.08.1972
• ISSN: 0804-4643; 1479-683X
• DOI: 10.1530/acta.0.0700625

ABSTRACT Isolated secretory granules from neural lobes of bovine hypophyses were incubated with tritiated lysine-vasopressin. Gradient centrifugation of these granules showed a difference in the distribution on the gradient of labelled vasopressin as compared with endogenous vasopressin, suggesting a heterogeneity of the granules in the homogenate. In other experiments the release from the granules to the medium of the tritiated hormone and of endogenous arginine-vasopressin was studied under various experimental conditions. Addition to the medium of calcium with or without ATP did not affect the release of hormone from the granules. ATP alone had no significant effect on the granular release of hormone. However, in the presence of an ATP-regenerating system (pyruvate kinase + phosphoenolpyruvate) ATP caused a slight, but significant increase in the release of endogenous vasopressin, whereas the release of labelled hormone was unchanged. Increasing the pH of the incubation medium caused an increased release of hormone from the granules. A similar effect was observed when the medium was cooled or when the osmolality was changed.