Renal structure and function in chronic experimental aortic coarctation in dogs treated with antihypertensive drugs.

The possible damaging effect on the kidneys of antihypertensive therapy in aortic coarctation was evaluated experimentally in eighteen canine puppies. Aortic coarctation was carried out in 13 puppies at the age of two months while sham-surgery was carried out on five control puppies. Six coarctated dogs were treated with hydrochlorothiazide, propranolol and prazosin. Antihypertensive therapy was started two months after the operation. Seven coarcted puppies did not receive any treatment. The dogs were followed up for 7 months after which fixation of the kidneys was performed. Antihypertensive therapy decreased blood pressure significantly although the level seen in the control dogs was not attained. There were no signs of deterioration of renal function. Neither light microscopic analysis nor electron microscopy revealed morphological abnormalities in the kidneys of any of the dogs. The present results show that active antihypertensive therapy in experimental coarctation, although not resulting in a normalization but in a significant lowering of blood pressure, is safe and does not cause any morphologic damage in the kidney before corrective surgery. The absence of juxtaglomerular hypertrophy supports the hypothesis that the renin-angiotensin system is not activated in chronic coarctation of aorta.