Langenbecks Archiv für Chirurgie vol:Suppl pages:135-9
Peak isovolumetric left ventricular pressure and dp/dtmax before and after norepinephrine (N.E.) infusion and cross-clamping of the aorta was identical in normal dogs and in dogs with chronic coronary artery occlusion (C.C.O.) before and after aortocoronary bypass. In normal dogs, coronary reserve was 7.9 and 7.4 times control for the subendocardium and the subepicardium. After C.C.O., coronary reserve was 7.0 and 5.7 times control in the normal area and 2.4 and 3.5 times control in the collateral dependent area (endo vs. epi). After N.E. myocardial blood flow increased to 57% of the coronary reserve in normal dogs, and to 100% in dogs with C.C.O. After bypass, myocardial blood flow normalized. In dogs with C.C.O., N.E. stimulated the contractile reserve maximally and the coronary reserve is completely expended.