Studies on the renin-angiotensin system in adrenal regeneration hypertension (author's transl)

Abstract

1) To clarify the role of adrenal enucleation on plasma renin activity (PRA), plasma renin substrate (PRS), PRA response to furosemide administration and vacular reaction to renin in adrenal regeneration hypertension (ARH), serial changes of PRA and PRS during adrenal regeneration, PRA response to furosemide administration, and pressor response to exogenous renin in ARH were investigated by comparison with those of intact rats, unilaterally adrenalectomized rats, and unilaterally nephroadrenalectomized rats with contralateral adrenalectomy or with contralateral adrenal exploration (control) on both tap water and high sodium intake. 2) The control rats drinking saline, when compared with intact rats drinking tap water, showed significant decreases in PRA and, concomitantly, significant increases in PRS throughout the experimental period. In the unilaterally nephroadrenalectomized rats drinking saline, two days after adrenal enucleation or adrenalectomy, a significant increase in PRA, with a concomitant decrease in PRS, was observed. Those changes were less pronounced in the adrenal enucleated group than in the adrenalectomized group. Ten days later PRA markedly decreased to the control level in both groups. PRS rose to the control level on the 10th day after adrenal enucleation without increasing further, while that in the adrenalectomized group remained as low as before. 3) No significant differences in any of the experimental groups were found in diuresis, natriuresis, or in changes in body weight and hematocrit during the one and a half hours after furosemide administration performed at the 9th experimental week. The basal PRA was significantly decreased in the other groups with unilateral nephroadrenalectomy and/or a high sodium intake as compared with the unilaterally adrenalectomized rats drinking tap water. The decrease in basal PRA was much more pronounced in the unilaterally nephroadrenalectomized rats drinking saline, with or without adrenal enucleation. After furosemide administration, PRA significantly increased in the unilaterally adrenalectomized rats drinking saline as well as in the unilaterally nephroadrenalectomized rats drinking tap water, with or without adrenal enucleation, while PRA values in three groups were only a half of the unilaterally adrenalectomized rats drinking tap water. An insignificant increase was found in the unilaterally nephroadrenalectomized rats drinking saline, independent of adrenall enucleation. 4) Pressor responses to hog renin in rats with ARH at the 10th postoperative day, and the 4th and 9th postoperative week did not show any significant differences as compared with those of intact rats drinking tap water and unilaterally nephroadrenalectomized rats drinking saline. 5) The effects of adrenal enucleation on PRA, PRS, PRA response to furosemide administration and pressor response to renin in ARH were discussed based on the observed results.