EFFECT OF ORTHO-IODO SODIUM BENZOATE ON HEMOGLOBIN-OXYGEN AFFINITY IN NORMAL AND ISCHEMIC MYOCARDIUM

  • 1 January 1977
    • journal article
    • research article
    • Vol. 203  (1) , 72-81
Abstract
The effect of o-iodo sodium benzoate (OISB) on the HbO2 dissociation curve of coronary venous blood was studied in an isolated canine heart preparation perfused at a constant coronary blood flow. Changes in P-50 (mm Hg) [the O2 tension (pO2) at which Hb is 50% saturated], were used to express Hb-O2-affinity. Intracoronary infusion of OISB (200, 400 and 800 mg/min) produced a dose-related increase in coronary venous P-50 and a concurrent increase in coronary venous pO2. OISB produced a significant decrease in heart rate and increase in coronary artery perfusion pressure. During cardiac pacing at 150, 190 and 230 beats/min, OISB (400 mg/min) significantly increased coronary venous P-50, myocardial O2 extraction (O2E) and O2 consumption (M.ovrhdot.VO2), whereas coronary venous pO2 was not changed. A 5-min intracoronary infusion of OISB (200 mg/min) during myocardial ischemia produced an increase in O2E, M.ovrhdot.VO2 and myocardial contractility with little change in coronary venous pO2. Acute pharmacological manipulation of the HbO2 dissociation curve may enhance O2 release to the myocardium while maintaining the effective driving pressure (as reflected in coronary venous pO2) for diffusion of O2 to the myocardium.