Douglas R. Gracey

Coronary pressure-blood flow relations: The effect of norepinephrine☆

Abstract Coronary pressure-blood flow relations were studied in anesthetized dogs by changing blood flow in the left main coronary artery and measuring coronary pressure before, during and after intracoronary norepinephrine infusion. Norepinephrine produced an increase in coronary vascular resistance in 10 of 28 experiments, usually in experimental preparations with a low initial coronary resistance. This increase in resistance occurred at different blood flow rates and was therefore not dependent on the rate of blood flow. Prior to norepinephrine infusion, coronary pressure-blood flow curves were curvilinear, convex to the pressure axis, showing a decrease in resistance with increasing blood flow except in those preparations with a low resistance in the control period. In these, resistance did not fall as flow increased from the low to the mid-flow range, but did fall as blood flow increased further.

The effect of lanatoside C on coronary vascular resistance

Abstract The effect of lanatoside C was studied in a preparation in which the flow of blood in the left main coronary artery could be accurately measured and varied. Lanatoside C produced an increase in left main coronary artery resistance at all rates of blood flow. The diluent of the drug did not affect coronary resistance. The increase in resistance persisted for the duration of the experiment. Some evidence is presented for a greater increase in resistance with larger doses.