Abstract
Saline perfused mesenteric arteries from rats of the New Zealand strain with genetic hypertension (GH rats) are more reactive to noradrenaline (NA) and 5 hydroxytryptamine (5-HT) than arteries from rats of the normotensive Otago stock colony (N rats). The rise in blood pressure to hypertensive levels in GH rats can be partially prevented by chronic sympathectomy from birth with 6 hydroxydopamine (6-HDA).
In N rats sympathectomy led to diminished responses to NA and 5-HT at all doses. In GH rats sympathectomy led to diminished responses to 5-HT at all doses but responses to NA were not reduced at the lower doses. This observation cannot be reconciled easily with the theory that vascular hypertrophy, secondary to high intraluminal pressures, is responsible for the enhanced vascular reactivity in hypertension: prevention of the development of high blood pressure in the GH rats by sympathectomy should have affected the responses to both NA and 5-HT in the same way.