SPATIAL FLUCTUATION OF REGIONAL MYOCARDIAL BLOOD FLOWS

Digital radiography (100 pixels/mm(2)) combined with the technique of H-3-labeled desmethylimipramine deposition was employed to visualize r egional blood flow distributions in rabbit left ventricular myocardium . A fluctuated pattern of myocardial flow and its dependence on arteri al oxygen tension (PaO2) was evaluated with the coefficient of variati on (CV) computed at each step of coarse-graining; flow images were rev isualized by increasing pixel area (PA) step by step from 0.01 to 1 mm (2). The CV values decreased with hypoxia at all resolution levels, su ggesting that there is a vascular regulatory mechanism for making myoc ardial perfusion uniform in response to decreased PaO2. In both perfus ion states, CV decreased with increasing PA. The relationship between CV and PA fitted the noninteger power law function, implying an appare nt fractality of CV.