EXPERIMENTAL DCA HYPERTENSION The author performed the histologic and histochemical study of the adrenal cortex, determination of 17-ketosteroids excretion in urine to investigate the relationship between experimental DCA hypertension and adrenal cortex.1) The first experiment The author divided male rats into three groups : Group 1, DCA 5 mg. parenterally and 0.85% NaCl solution by mouth; Group 2, 2% NaCl mixed with the diet and 0.85% NaCl solution by mouth; Group 3, control, 0.85% NaCl solution alone by mouth. Unilateral nephrectomy was performed in the halves of experimental animals.2) The second experiment The author divided male rats into three groups : Group 1, DCA 5 mg. parenterally and 1% NaCl solution by mouth; Group 2, DCA 5 mg. parenterally and tap water by mouth; Group 3, control, 1% NaCl solution alone by mouth. Unilateral nephrectomy did not produce any appreciable effect on blood pressure. In the course of the first and second experiments, the author performed the clinical examinations including the measurement of blood pressure, fluid intake, urinary volume, body weight, urinalysis and urinary excretion of Cl and 17-ketosteroids.After the animals were sacrificed, the author performed the histologic and histochemical examination of the adrenal cortex.The summary and conclusion of this study are as follows : 1) The administration of DCA together with NaCl could produced a marked hypertension which sustained at the level of 200 mm. Hg. The administration of DCA alone could also produce a hypertension, but the elevation of blood pressure was slight as compared with the case of both DCA and NaCl administration. From these results, it is assumed that DCA hypertension would develop through the intermediate of NaCl.2) Adrenal cortical changes occurred in experimental DCA hypertensive rats were similar to those in salt hypertension, and those changes were a progressive disuse atrophy of zona glomerulosa in proportion to the amount and duration of the administration of DCA. Atrophy of the zona glomerulosa was more pronounced in the case of both DCA and NaCl administration than in the case of DCA administration alone.There appeared an enlargement of the outer part of the fasciculata which is considered the sign of stress and an increased urinary 17-ketosteroids excretion in the case of both DCA and NaCl administration. However, no relation was found between stress and elevation of blood pressure. From the changes of zona glomerulosa, it is assumed that the adrenal cortex would not secrete the mineralocorticoids in DCA hypertension similarly as in salt hypertension, and that this zone would not be concerned with DCA hypertension.OVERALL CONCLUSIONS FROM THE STUDY OF ADRENAL CORTICAL FUNCTIONS IN EXPERIMENTAL HYPERTENSIONS.The histologic and histochemical study of the adrenal cortex, determination of urinary 17-ketosteroids excretion were performed in order to investigate the adrenal cortical function in various types of experimental hypertensions. The author obtained the following conclusions.The zona glomerulosa showed hyperfunction in the hypertension due to denervation of the pressoreceptors and renal hypertension, while hypofunction in the salt and DCA hypertensions. These findings indicate that this zone would not be active factor in the development of hypertension. Therefore, the theory of renin-adrenal axis would not be extended to the general sphere of hypertension.The zona fasciculata reacted sensitively to the stress and presented histological alterations almost proportionately to the change in urinary 17-ketosteroids excretion, accordingly, the author cannot postulate any relationship between zona fasciculata and hypertension, and the idea of disease of adaptation could not be applied to hypertension.