β-adrenergic stimulation of mouse parotid gland: Amylase activity and secretory granules during isoproterenol-induced mitosis

1. 1. This paper examines the mitotic activity of parotid glands of groups of mice sacrificed at 1 hr-intervals between 26 and 36 hr after being injected with dl-isoproterenol (IPR, 1 μmol/g, single dose, i.p.). 2. 2. Maximal mitotic activity occurs 35 hr after IPR injection; there is a concomitant rise of amylase activity (64% over control). 3. 3. Mitotic cells showed increased number of secretory granules (N) with regard to interphasic cells. However, the increment of N is paralleled by an increment of the cell section area (A); the N A ratio is thus maintained around 0.45 throughout. 4. 4. These findings suggest that during IPR-induced mitosis of mice parotid cells there is not a blockade of the biosynthetic pathways which lead to the appearance of secretory granules in the cell cytoplasm.