[Coronary autoregulation of the isolated rabbit heart]

The autoregulation behaviour of the coronary circulation was studied on an isolated Langendorff-heart of rabbit. Static pressure-flow curves were recorded for the normal and maximally dilated vascular system. For analyzing the dynamics of autoregulation of the flow to pressure jumps within the autoregulation range was measured. Modelling was performed by means of the linear system theory, assuming first-order transfer functions for the contraction and dilatation process co-acting in the regulation. The system parameters were determined in the time-range by adapting a bi-exponential function to the measured data. For the dilatation reaction following pressure fall a mean time constant of 5.4 s was measured, while a time constant of 146.8 s was found for the counterregulation (constriction). These events are discussed with regard to possible further studies on the pharmacology of coronary regulation.