Modulation of the arterial baroreceptor reflex by the vasopressin receptor in the area postrema of the hypertensive rats

The role of arginine 8-vasopressin (AVP) in regulation of the baroreceptor reflex in the area postrema was examined in anesthetized hypertensive rats. The sensitivity of the baroreceptor reflex in a one-kidney one clip (1K1C) hypertensive rats was increased in only the initial stage (2 weeks), in association with increase in blood pressure, and then returned to the normal level. This increase in the sensitivity of the baroreceptor reflex in the initial stage was reversed by microinjection of a V1 or V2 antagonist (1 μg) into the area postrema. AVP V2 receptor mRNA was expressed temporarily in the area postrema in this period. These results suggest that vasopressin receptors in the area postrema is important in regulating the sensitivity of the baroreceptor reflex.