Deparfment of Pharmacology, Cassella A G, Frankfurt/M., W. Germany Comparison of various methods for assessing infarct- size in the dog

Summary Various methods used for the assessment of infarct-size were compared in a canine model of coronary artery occlusion. The ability of molsidomine (an antiangihal agent) to reduce infarct-size was also investigated. Open-chest dogs underwent occlusion of the left anterior descending coronary artery and starting 30 rain after the occlusion received either molsidomine (n = 8) as an infusion at the rate of 1 ~g/ kg/min for 30 rain and at a rate of 0.75 ~g/kg/min for 2 h, or saline (controls, n = 8). Three hours after the occlusion methylene blue was injected into the left atrium for the assessment of the area at risk in vivo (ARV). The animals were then sacrificed, the heart removed and coronary arteriograms made after injection into the left coronary ostium of a BaSOcgelatin mass to delineate the post-mortem area at risk (ARPM). The hearts were then cut in sections and the infarct's (I) area visualized with nitrobtue tetrazolium Cl. The left ventricle (LV) and I were also weighed. ARV, ARPM as well as LV and I areas were determined by planimetry. Body weight and LV mass were similar in both groups, I mass however, was markedly lower in molsidomine than in control dogs. Percentages I/LV mass and area were also significantly lower in the treated than in the control animals, and there was a significant correlation between the mass and planimetric methods for determining I size. ARPM/LV % was similar in both groups and I/ARPM % was smaller in molsidomine than in control animals, however this difference was not statistically significant. Molsidomine markedly reduced ARV/LV % which resulted in similar I/ARV ratios both in the treated and control groups. It is concluded: (1) that the direct measurement of I (mass) or the percentages I/ LV mass or area are similarly useful for the detection of a pharmacological effect of I size. ARPM is unaffected by drug treatment and thus provides a valid reference point for the assessment of I. ARV may be altered by a pharmacological intervention and thus may give false negative results when used as the basis for expressing I size. (2) Molsidomine is a potent agent for reducing I size.