Abstract
EXPERIMENTAL ENDOCRINE HYPERTENSION Among the endocrine glands, adrenal glands are considered to play a most important role in hypertension. Since Goldblatt observed for the first time that bilateral adrenalectomy interfered with the development or maintenance of experimental renal hypertension, the role of the adrenal cortex in hypertension has been discussed. Experimentally, since it is difficult to produce hypertension in dogs by administration of adrenal cortical hormones (DCA ets.), it was in this study attempted to produce a persistent hypertension by ligation of the adrenal veins in dogs. It was the purpose of this study to examine whether a surgical procedure on the adrenal in the natural state can cause hypertension.In this study, 13 trained dogs were used for the operation, which was performed on one side of adrenal glands and after 1-2 weeks on the other side. Blood pressure was measured directly on the femoral artery by mercury manometer. Effective renal plasma flow, glomerular filtration rate and filtration fraction were determined by renal clearance technique. At the same time, plasma Na and urine Na were measured.In some cases blood pressure was elevated after ligation of adrenal veins in one side, while the added operation on the other side showed a depressor effect. In others, the operation on both sides produced slight sustained hypertension. At that time RPF increased (10-70 %), GFR increased (25-90 %) and FF was unchanged, but the reabsorption of sodium in kidneys increased in most hypertensive animals. The histochemical study of adrenal cortex revealed signs of hyperfunction in zona glomerulosa.According to these results, the increase in amount of sodium reabsorption due to hyperfunction of zona glomerulosa is considered to play a great role in the pathogensis of hypertension.In conclusion, the above-mentioned results suggest that the patterns of Cushing's syndrome as well as Addison's disease may be produced artificially. It is assumed that the adrenal cortex is intimately concerned with sodium metabolism, where the retention of Na would be a factor in the pathogenesis of endocrine hypertension.EXPERIMENTAL NEUROGENIC HYPERTENSION In the opinions of many investigators, the nervous system occupies the domainant place in maintaining the elevated blood pressure during the chronic stage of hypertension, and humoral agents merely initiate the rise during the first few weeks of hypertension. The term "neurogenic" is used broadly, but usually "neurogenic" suggests the sympathetic component of the autonomic nervous system.Here, the participation of neurogenic factor in hypertension and its mechanism were studied by the section of buffer nerves and by using ganglionic blocking agents and adrenolytic agents.In pressoreceptor deneving hypertension, I attempted to study the elevation of blood pressure in its relation to the RPF, renal vascular resistance and GFR, and to study its mechanism. In this study, 10 trained dogs were used. Among them, 1 showed slight, 2 moderate and 4 marked hypertension. Percentage of success was 70 %. If the cases with transient elevation of blood pressure were included in the group of success, the percentage of success was 100 %.The elevated blood pressure reached a peak within one week after operation. The blood pressure fluctuated, but bacame sustained during weeks, and then decreased gradually. In some cases, the elevated blood pressure continued for over one year.Renal plasma flow increased along with the development of hypertension in all animals (7-43 %, average 22 %), but was not parallel with blood pressure and so renal vascular resistance increased.In conclusion, the hypertension due to section of buffer nerves may belong to the pheochromocytoma type, and its initiating mechanism is probably secretion of adrenalin and/or nor-adrenalin.
