Neurohypophyseal Responsiveness in the Hypertensive Rat

¹ From the Department of Anatomy, The University of British Columbia, Vancouver, Canada

Neurohypophyseal responsiveness in normotensive and hypertensive rats was studied using a standardized intracarotid injection of a sodium chloride solution as osmotic stimulus. The response was judged by measuring the rate of urine flow before and after stimulation. Rats under DCA treatment for 3 or 6 months, as well as rats with permanent post-DCA hypertension or with spontaneous senescent hypertension were used in four separate experiments. All experiments showed the neurohypophysis of the hypertensive groups to be more responsive than its control. This is interpreted to mean that the secretion of antidiuretic hormone is inhibited and tends to accumulate in hypertension.