On the noradrenaline reaction of the adrenal medulla in experimental hypertensive rats, especially in spontaneously hypertensive rats. I. Histochemical and histometrical studies on the noradrenaline storing cell islets of the adrenal medulla in various experimental hypertensive rats.

Abstract

Spontaneously hypertensive rats, renal hypertensive rats, DCA hypertensive rats, neurogenic hypertensive rats and control rats totalling 360 were killed under minimum stress. The noradrenaline in the adrenal medulla was stained by COUPLAND et al.'s glutaraldehyde osmium tetroxide method and the dimensional changes of noradrenaline storing cell islets were studied. In this experiment, spontaneously hypertensive rats were divided into four stages through their survival duration : until 30th day after birth, the 40th to 60th day after birth, the 5th to 7th month after birth and over one year after birth. Renal hypertensive rats, DCA hypertensive rats and neurogenic hypertensive rats were divided into four stages: the prehypertensive stage, the early stage of the 5th to the 24th day after operation, the middle stage of the 3rd month after operation and late stage of the 6th month after operation. Findings in spontaneously hypertensive rats, renal hypertensive rats, DCA hypertensive rats and neurogenic hypertensive rats were compared with those in control rats with almost the same survival duration. (1) The noradrenaline storing cell islets in the adrenal medulla became stainable from the 6th day after birth in both cases of spontaneously hypertensive rats and control rats. After that, the intensity of staining became stronger and after the 15th day, it maintained constant intensity. (2) The area of noradrenalune storing cell islets of the adrenal medulla in spontaneously hypertensive rats on the 6th day after birth was 9.6 per cent, about 1.2 times as large as that of control rats (8.1%) and after that as days passed, the area became larger. On the 10th day, that of spontaneously hypertensive rats was 14.1 per cent, about 1.5 times as large as that of control rats (9.1%), on the 18th day, 21.7 per cent, about 2 times as large as that of control rats (10.5%), and after that the state was constant until one year after birth, when it decreased a little. Spontaneously hypertensive rats develop hypertension in the 8th week after birth while the area of noradrenaline storing cell islets in the adrenal medulla becomes about 2 times as large as that of control rats before the development of hypertension, and this state remains constant after the development of hypertension. (3) As for the area of noradrenaline storing cell islets in the adrenal medulla of renal hypertensive rats, DCA hypertensive rats and neurogenic hypertensive rats, the following results were obtained : (a) In the prehypertensive stage, the areas in three kinds of hypertensive rats did not increase as in the case of spontaneously hypertensive rats, and there was no significant difference from that of control rats. (b) However, the area of noradrenaline storing cell islets in the adrenal medulla increased immediately after the development of hypertension. (i) Renal hypertensive rats showed an increase in the area; 17.8 per cent in the early stage, 17.9 per cent in the middle stage and 19.1 per cent in the late stage, and their values were 1.3 times, 1.5 times and 1.6 times as large as that of control rats. (ii) In the case of DCA hypertensive rats, the area was 19.9 per cent in the early stage, 20.5 per cent in the middle stage and 20.4 per cent in the late stage, showing an increase of 1.4 times, 1.6 times and 1.7 times in comparison with that of control rats. (iii) In the case of neurogenic hypertensive rats, the area was 21.4 per cent in the early stage, 23.5 per cent in the middle stage, 26.3 per cent in the late stage, and was 1.4 times, 1.7 times and 1.8 times as large as that of control rats, respectively, that is, in renal and DCA hypertensive rats, the grade of increase in the area was always smaller than that of spontaneously hypertensive rats but neurogenic hypertensive rats showed almost the same value as that of spontaneously hypertensive rats in the late stage. (c) The intensity of staining of noradrenaline storing cell islets did not show any difference fr