L-Triiodothyronine and Dinitrophenol-Induced Hypertension

Abstract

Summary

The data support previous results showing that L-triiodothyronine (T₃) accelerates the production of sodium chloride hypertension. Dinitrophenol (DNP) with NaCl produces hypertension rapidly, however, it did not result in a sustained elevation of blood pressure. The ability to produce hypertension with T₃-NaCl was dependent upon the use of weanling animals, whereas it was not for DNP-NaCl hypertension. These disparities in results suggest that the two drugs probably aided the induction of hypertension by different mechanisms. In addition, temporary reversal of hypertension with methimazole and lack of effect on hypertension after thyroidectomy indicate the thyroid is not necessary for the maintenance of T₃-NaCl hypertension.

Acute hypertension that resulted from DNP and salt was not dependent upon the age of the animals. A second administration of the two materials starting at 7 weeks of age produced a similar response, a.s when given to weanling rats. The T₃ hypertension could not be produced in the same group of rats at the age of 14 weeks, which suggested that age was a factor in T₃-NaCl hypertension.

In the study designed to evaluate the effect of age on the ability to produce hypertension with T₃ and salt, rats 9 weeks of age failed to become irreversibly hypertensive. This supports a previous report that sexually immature rats must be used in order to produce hypertension with T₃-NaCl treatment (3). This suggests that T₃ affects an underdeveloped system in the weanling rat. In contrast DNP-NaCl hypertension can be produced in sexually mature animals, which is additional evidence that T₃ and DNP affect different mechanisms in the accelerated production of salt hypertension.

The author wishes to thank Mr. Harold Roeder for his technical assistance.