Correlation of physical and morphological parameters with release of catecholamines, ATP, and protein from adrenal medulla chromaffin granules

Abstract

Exchanging 0.3 M sucrose for 0.3 M glycerol as the bathing medium for isolated bovine adrenal chromaffin granules at 0 degrees C or raising the temperature of granules suspended in 0.3 M sucrose to 37 degrees C causes the release of catecholamines, ATP and soluble protein stored in the granules. These treatments also reduce the turbidity (absorbance at a non-absorbing wavelength) of the same suspensions. The glycerol-induced release is shown by morphology and morphometry to be due to lysis of the granules. Advantage is taken of the difference in density of the intact granules and the granule ghosts to confirm this result by centrifugation of glycerol-incubated samples on continuous gradients of sucrose and metrizamide. Similar centrifugation experiments performed on the granules incubated in sucrose at 37 degrees C show that lysis also accounts for the fast phase of release of granule contents, and not graded selective release of material from otherwise intact granules.