Gd-DOTA tubular transit asymmetry induced by angiotensin-converting enzyme inhibitor in experimental renovascular hypertension.

In stenosis of a renal artery, angiotensin-converting enzyme inhibitor (ACEI) can induce a decrease in ipsilateral glomerular filtration. Dynamic MR imaging with gadolinium chelate enhancement was tested to detect this glomerular filtration reduction in experimental renovascular hypertension in the rat. Thirteen rats, with surgically induced left renal artery stenosis, developed hypertension and were studied before and after intravenous injection of ACEI with sequential Gd-DOTA-enhanced MR imaging. The time to onset of the tubular phase, the time of the maximal drop of signal, and the medullary signal-time curves of both kidneys were compared. Before ACEI, tubular phases were symmetric in 11 rats and slightly asymmetric in 2. Twelve rats showed ACEI-induced changes (positive test): absence of tubular phase on the left side (n = 8) or delay (n = 4) with significant differences (P < .01). Tubular phases remained symmetric in one (negative test). Dynamic MR imaging can identify ACEI-induced Gd-DOTA tubular transit asymmetry, indicative of functionally significant renal artery stenoses, in rats.