Enalaprilat-enhanced renography in a rat model of renovascular hypertension.

Abstract

The effect of rapid converting enzyme inhibition (CEI) with intravenous enalaprilat on technetium-99m-(99mTc) diethylenetriaminepentaacetic acid (DTPA) and 99mTc-dimercaptosuccinic acid (DMSA) renograms was evaluated in rats with two-kidney, one-clip renovascular hypertension. Rapid sequential DTPA renograms, performed immediately before and five minutes after enalaprilat injection (30 micrograms/kg), demonstrated a selective decrease in clipped kidney DTPA plasma clearance following CEI and no significant effect on unclipped kidney function. Pre- and post-CEI data were obtained with a single injection of DMSA by administering enalaprilat five minutes after the radiopharmaceutical. Enalaprilat slowed the rate of DMSA accumulation in clipped relative to unclipped kidneys, and reduced the clipped/unclipped kidney ratio of absolute DMSA uptake at 10 and 30 min. DTPA and DMSA were equally effective in demonstrating the CEI effect. Enalaprilat was also compared with captopril (3 mg/kg, intraperitoneally), using sequential DTPA renograms. Clipped kidney DTPA plasma clearance was reduced to an identical degree (40%) by both converting enzyme inhibitors. Clinical renographic protocols can probably be devised to take advantage of the rapid, reliable CEI of enalaprilat, thereby shortening total procedure time.