Comparison of effects of thyroidectomy with propylthiouracil treatment on renal hypertension in rats

¹ Departments of Physiology and Anatomy, University of Florida, College of Medicine, Gainesville, Florida

Surgical thyroparathyroidectomy (thyroidectomy) prevented the rise in systolic blood pressure to hypertensive levels in rats whose kidneys were bilaterally encapsulated with latex envelopes. This treatment also reduced the systolic blood pressure of ‘normal,’ nonencapsulated rats. The antithyroid drug, propylthiouracil (PTU), acted in the same fashion as surgical thyroidectomy on blood pressure of both kidney encapsulated and nonencapsulated rats. However, PTU appeared to be a more effective treatment than thyroidectomy since blood pressures of both PTU-treated, kidney encapsulated and PTU-treated, nonencapsulated rats were reduced to a greater extent than were the blood pressures of their surgically thyroidectomized counterparts. It was not possible to lower further the blood pressure of surgically thyroidectomized, kidney-encapsulated rats by treatment with PTU, even though the treatment was continued for 20 weeks. Other results of the two treatments were also similar and differed only in degree, viz. decreased growth rate, decreased food intake and anemia. Surgical thyroidectomy decreased water intake of nonencapsulated rats while PTU treatment increased it above that of controls. In the encapsulated groups, however, both treatments decreased water intake below that of control encapsulated rats. Thyroidectomy performed after the kidneys had been encapsulated for 9–19 weeks had only slight effect on blood pressure.