Evaluation of the control function of interstitial osmolarity in coronary autoregulation.

A control mechanism for the control of coronary blood flow (especially coronary autoregulation), presuming that interstitial osmotic pressure determines vascular resistance, was critically examined. A theoretical model of the control mechanism was made and the most important parameters of this theoretical model were estimated from published data. The parameters are the slope of coronary autoregulation curves, the sensitivity of coronary resistance to plasma oncotic pressure and capillary resistance. It appeared that the gains of this control loop were not large enough to allow for a dominant role of interstitial osmolarity in coronary autoregulation.