EFFECTS OF IOMEPROL, A NEW NONIONIC CONTRAST-MEDIUM, VIS-A-VIS IOPAMIDOL AND NITROGLYCERIN, ON CORONARY DIAMETER AND BLOOD-FLOW IN CHRONICALLY INSTRUMENTED DOGS

The effects of an intracoronary administration of iomeprol, a new noni onic tri-iodinated water-soluble contrast medium, on coronary circulat ion were compared to those of iopamidol and those of nitroglycerin in 6 chronically instrumented conscious dogs. A pair of 10 MHz piezoelect ric crystals and an electromagnetic flow probe were placed on the left circumflex coronary artery (LCCA) to measure the epicardial coronary diameter (CD) and coronary blood flow (CBF). Polyethylene tubing for d rug administration was inserted into the LCCA proximal to the sonomicr ometers. Iomeprol at the dose of 1 ml and 3 ml/min for 1 min significa ntly increased CD by 0.6 +/- 0.1% and 1.4 +/- 0.3%, respectively and C BF by 44.5 +/- 9% and 70 +/- 10%, respectively. Iopamidol at the same rates also significantly increased CD by 0.8 +/- 0.1% and 1.5 +/- 0.3% and CBF by 50 +/- 11% and 82 +/- 14%, respectively. There was no stat istically significant difference between iomeprol- and iopamidol-induc ed increases in CD and CBF. However, the duration of the increase in C D was significantly shorter (p < 0.05) after iomeprol than after iopam idol. Nitroglycerin (10 mug/kg) significantly increased CD by 4.5 +/- 1% and CBF by 105 +/- 10%. The increases in CD and CBF in response to iopamidol and iomeprol were significantly smaller (p < 0.01) than to n itroglycerin. We conclude that vasodilating effects of iomeprol and io pamidol on the large epicardial coronary artery and coronary blood flo w are comparable in conscious dogs and significantly lower than after nitroglycerin in the doses used by us.