J Korean Med Sci.  2005 Oct;20(5):732-739. 10.3346/jkms.2005.20.5.732.

Effects of Inotropic Drugs on Mechanical Function and Oxygen Balance in Postischemic Canine Myocardium: Comparison of Dobutamine, Epinephrine, Amrinone, and Calcium Chloride

• Yoo KY
• Kim H
• Jeong CW
• Park HC
• Bae HB
• Lee JU

• KMID: 1781753
• DOI: http://doi.org/10.3346/jkms.2005.20.5.732

Abstract

Brief ischemic episodes that induce myocardial and coronary endothelial dysfunction may alter the responses to inotropic drugs. To determine the effects of inotropic drugs in stunned myocardium, the coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and regional mechanical function in response to intracoronary dobutamine, epinephrine, amrinone, and calcium chloride (CaCl2) were measured before (normal) and 30 min after a 15-min-period occlusion of the left anterior descending artery (stunned) in an open-chest canine model. Percent segment shortening (%SS) and post-systolic shortening (%PSS) were determined. Myocardial extraction of oxygen (EO2) and lactate (E(lac)) was calculated. The inotropic drugs increased %SS, CBF, and MVO2 in normal myocardium. Epinephrine and amrinone decreased, while dobutamine and CaCl2 did not affect EO2. The ischemia and reperfusion itself significantly reduced %SS and E(lac), and increased %PSS. In stunned myocardium, the responses to inotropic drugs were not significantly altered, except that they progressively reduced %PSS and epinephrine did not affect EO2. These findings indicate that a brief episode of ischemia does not affect the mechanical and metabolic coronary flow responses to inotropic drugs, although it abolishes direct vasodilator responses to epinephrine.

Keyword

Heart; Coronary Circulation; Inotropic; Reperfusion Injury; Animal Experimentation; Dogs; Dobutamine; Amrinone; Calcium Chloride; Epinephrine

MeSH Terms

Amrinone/administration and dosage
Animals
Calcium Chloride/administration and dosage
Cardiotonic Agents/*administration and dosage
Comparative Study
Dobutamine/administration and dosage
Dogs
Dose-Response Relationship, Drug
Epinephrine/administration and dosage
Female
Male
Myocardial Contraction/*drug effects
Myocardial Stunning/*drug therapy/etiology/*physiopathology
Oxidation-Reduction/drug effects
Oxygen Consumption/*drug effects
Reperfusion Injury/complications/*drug therapy/*physiopathology
Treatment Outcome

Figure

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  Fig. 1 Schematic presentation of the experimental preparation. LAD, left anterior descending coronary artery; LCX, left circumflex coronary artery; IVC, intravenous catheter; IAC, intra-arterial catheter; UDT, ultrasonic dimension transducers.

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  Fig. 2 Effect of intracoronary infusion of incremental doses of dobutamine (n=11), epinephrine (n=10), amrinone (n=10) or calcium chloride (n=11) on myocardial oxygen extraction before (normal) and after a 15-min of coronary occlusion and subsequent reperfusion (stunned) in dogs. Pre-baseline, preischemic baseline values; post-baseline, postischemic baseline values. Values are mean±SD. p<0.05 vs. *corresponding baseline values; vs. †amrinone.

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  Fig. 3 Effect of intracoronary infusion of incremental doses of dobutamine (n=11), epinephrine (n=10), amrinone (n=10) or calcium chloride (n=11) on myocardial lactate extraction before (normal) and after a 15-min of coronary occlusion and subsequent reperfusion (stunned) in dogs. Pre-baseline, preischemic baseline values; post-baseline, postischemic baseline values. Values are mean±SD. p<0.05 vs. *corresponding baseline values; vs. †normal myocardium and vs. ‡epinephrine.

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