Myogenic reactivity and resistance distribution in the coronary arterial tree: a model study

The objectives of this study were to evaluate the myogenic behavior of bloo d vessels and their interaction within the coronary arterial tree and to ev aluate the possible role of the myogenic response in autoregulation. The mo del consists of 10 compartments in series, each representing a class of ves sel sizes. Diameter and resistance in each class are determined by their va lue at full dilation (d(p), R-p) and by the myogenic response. Three distri butions of R-p and three distributions of myogenic strength, M-i (slope of pressure-diameter curve, range -0.05 to -0.4%/mmHg) were evaluated (9 cases ). It was found that larger vessels attenuate the myogenic activity of smal ler vessels and that myogenic responsiveness is sufficient to achieve autor egulation. When M-i has a maximum in vessels of 84 mu m, the maximum effect of perfusion pressure on active diameter occurs in vessels between 123 and 181 mu m, depending on the distribution of R-p. Distribution of resistance and control mechanisms in the coronary arterial tree are important for int erpretation of individual vessel responses as observed in vivo.