Limitation of coronary perfusion of different degree induces inhomogeneous changes in resistance of vessels in the hypoperfusing zone: an adequate dilatory regulatory reaction may be followed by an increase in resistance of the coronary vessels. An active component of diastolic coronary resistance used to analyze vascular reactions, rate and character of changes in resistance under conditions of coronary perfusion as well as histological and electron-microscopic estimation of the vascular wall state testify to reversibility and active character of the observed changes in coronary resistance including its increase. This increase is pathogenetically significant as it may induce further development of the coronary perfusion disorder.