The characterization and assay of enzymes in rat adrenal cortex. I. Esterase and phosphatase activities.

There is evidence that significant changes may take place in the activities ofenzymes present in secreting glands under the influence of regulatory hormones. Gutman & Gutman (1938) reported increases in the acid phosphatase activity of prostate during the development of the epithelia induced by testosterone. According to Fuenzalida (1949), prolonged oestrogen treatment causes an increase in alkaline phosphatase activity in guinea pig uterus. Large increases in arginase and alkaline phosphatase activities in the mammary gland during lactation have been found by Folley & Greenbaum (1947). Evidence regarding the nature of similar changes taking place in the adrenal cortex has been largely histological. Characteristic alterations in lipid metabolism in this gland in the rat, following hypophysectomy, were indicated by the work of Reiss, Balint, Oestreicher & Aronson (1936). Variations in alkaline phosphatase content under different endocrine conditions have been investigated in the moupe and rat by Elftman (1947) and by D,erjp'ser , Greep & Deane (1949). Chemical studies# however, have so far been limited, though isolated observations, sometimes of a qualitative kind, have from time to time been reported. The presence of a lije (i.e. tributyrinase) in the tissue was demonstatbd by Cheboksarov & Malkin (1927) and by Scoz & Mariani (1939); this would seem to be of importance in relation to the lipid changes observed by Reiss et al. (1936). Chemical proof of the existence of an adrenal cortical phosphomonoesterase has also been furnished (Granger & Bessoles, 1945). A knowledge of the properties of the various enzyme systems present in the adrenal cortex, and the manner in which they are influenced by different endocrine factors, may be important in connexion with the processes governing the secretory activity of the gland. Investigations on these lines have accordingly been initiated, and the present paper contains an account of the experimental work so far carried out to characterize the lipase and phosphatase activities shown by aqueous homogenates of adrenal cortical tissue, and to devise suitable methods for their accurate assay in small quantities of tissue. Since tributyrin has been used as the principal test substrate for lipase, the latter will be