Vascular reactivity to angiotensin and noradrenaline in rats. Effect of aging and of uninephrectomy.

The effects of angiotensin II (ATII), and noradrenaline (NA) were measured in vivo and in several vascular preparations taken from normotensive intact or from uninephrectomized rats receiving NaCl 0.9% for drinking. The study was directed to evaluate the effects of aging and of uninephrectomy plus NaCl administration on vascular reactivity. Aging neither change the response in vivo or the myotropic effects of the agents in the isolated portal vein, while the effect of ATII was specifically increased in the perfused kidney, and both the response to ATII and NA were decreased in rat hindquarters and thoracic aortae. Uninephrectomy and NaCl administration were accompanied by a selective increase of sensitivity to ATII in vivo and in the isolated kidney, by a stronger effect of both ATII and NA in the hindquarter, while the response of the portal vein did not change and those of the thoracic aorta to ATII and NA showed a tendency to diminish. These results indicate that aging and uninephrectomy have to be taken into account in studies intended to evaluate the sensitivity of vascular preparations of normotensive and hypertensive rats.