Modified cardiovascular sensitivity of the area postrema to vasopressin in spontaneously hypertensive rats

Vasopressin has been shown to act at the area postrema to increase the sensitivity of the baroreceptor reflex. We have previously demonstrated that microinjection of vasopressin into the area postrema of Sprague-Dawley rats elicits pressor effects. We report here that vasopressin microinjection into the area postrema of spontaneously hypertensive rats is without effect on blood pressure, whereas microinjection into age-matched Wistar-Kyoto controls results in significant increases in blood pressure at 50 and 100 pg. These results suggest an altered sensitivity of the area postrema to vasopressin in this genetic model of hypertension.