[Role of coronary vessel reactivity in regulating myocardial blood supply].

Coronary vascular reactivity to transitory myocardial ischemia was investigated in experiments on isolated canine heart perfused by donor blood. The investigation was performed under different cardiac functional activity regimens conditioned by a stepwise increase of volume loading. The obtained results showed that myocardial blood supply rise was accompanied by an increase in maximum reactive blood flow within the ascending arm of the ventricular function curve. On the curve plateau, a further coronary blood flow increase was combined with reduced reactive hyperemia. Left-ventricular overloading was associated with a reduction in both working hyperemia and coronary reserve. The findings demonstrate that changes in heart function are accompanied with changes in the reactivity of coronary vessels that contribute to the regulation of adequate blood supply of the heart and largely determine coronary dilative reserve and its potential realization.