In Langendorff-perfused guinea pig hearts, local myocardial perfusion was evaluated by analysis of FITC-dextran-150 elution kinetics after bolus injection. Locally estimated half-times of the monoexponential elution curves showed good correlation with global undisturbed coronary flow. After ligation of the left anterior descending coronary artery indicator transit kinetics in the ischemic area were only slightly affected (increase of t/2 by 30 +/- 19%), indicating a residual flow of 80% to the ligated area. The moderate increase (40 +/- 20%) of NADH-surface fluorescence in the same area confirms a high degree of residual flow. Indicator partition volume (signal peak height after bolus injections) was additionally enhanced. Moreover, indicator transit kinetics changed from monoexponential to composed kinetics. On reperfusion these effects were partially reversible. Ligation of the left coronary artery at its aortic root produced only moderate ischemia, indicating very effective mechanisms in the isolated guinea pig heart from the right coronary artery to support the left ventricle. Severe ischemia as evidenced from NADH-surface fluorescence could be observed only after "stopped flow" ischemia.

SummaryIn isolated guinea pig hearts epicardial perfusion was estimated by analysis of the transit profile of different fluorescence indicators. Several coronary dilating agents were tested with regard to their influence on local perfusion kinetics revealing distinct patterns of microcirculatory drug action.