Intravertebral angiotensin II inhibits cardiac vagal efferent activity in dogs.

The effect of intravertebral infusion of angiotensin II on cardiac vagal efferent activity was studied in anesthetized mongrel dogs. Unilateral infusion of doses of angiotensin II as low as 5 ng/kg/min inhibited basal vagal tone and also decreased the slope of the relationship between cardiac vagal efferent activity and systolic blood pressure. Intravenous and intracarotid infusion of similar doses of angiotensin II produced little or no inhibition of vagal tone. These results demonstrate directly that angiotensin II can act centrally to inhibit cardiac vagal efferent activity and provide additional evidence that the increase in blood pressure produced by intravertebral angiotensin II results, at least in part, from decreased vagal tone to the heart.