Angiotensin sensitivity and prostaglandins in dogs with renal hypertension

During established two-kidney one clip hypertension in dogs blood pressure is elevated despite only slightly raised plasma renin activity. Dose dependent effects of exogenous angiotensin II on systemic and renal haemodynamics were examined before and after induction of this type of hypertension in conscious dogs. There was no difference in the response of blood pressure to angiotensin II in each group, suggesting that altered pressor sensitivity to angiotensin II is not the cause of the persisting hypertension. However sodium excretion, effective renal plasma flow and glomerular filtration rate were all decreased by angiotensin II in the normotensive group, but were unchanged or increased in the hypertensive group. Renal prostaglandin E excretion was also increased in the hypertensive animals, and further increased during infusion with angiotensin II. The altered renal response to angiotensin II in the hypertensive group may reflect changes in occupancy of angiotensin II receptors and/or enhanced renal release of vasodilator prostaglandins.