Relations of Polyuria and Polydipsia in Experimental Diabetes Insipidus

Abstract Hypothalamic radio‐frequency lesions were produced in unanesthetized goats with the use of thermo‐couple electrodes permanently implanted into the median eminence region. Lesions restricted to the median eminence induced the triphasic response typical of experimental diabetes insipidus (DI). The polyuria of the temporary phase of DI developed before the polydipsia commenced. The increased water intake was apparently secondary to the excessive renal water loss. When the median eminence lesions were extended into the midhypothalamic region no clear distinction could be made between the onset of polyuria and polydipsia. Similar lesions encroaching upon the anterior hypothalamus and affecting the paraventricular nuclei, caused temporary hyperdipsia but no transient polyuria, or a much delayed temporary increase in urine flow. All three types of lesions induced the permanent phase of DI after a latent period of 6 to 11 days. The polydipsia of the permanent phase occurred after the commencement of the polyuria (observations in 2 animals), and was evidently due to a physiological stimulation of the thirst mechanism.