Transmural distribution of metabolic abnormalities and glycolytic activity during dobutamine-induced demand ischemia.

Abstract

The heterogeneity across the left ventricular wall is characterized by higher rates of oxygen consumption, systolic thickening fraction, myocardial perfusion, and lower energetic state in the subendocardial layers (ENDO). During dobutamine stimulation-induced demand ischemia, the transmural distribution of energy demand and metabolic markers of ischemia are not known. In this study, hemodynamics, transmural high-energy phosphate (HEP), 2-deoxyglucose-6-phosphate (2-DGP) levels, and myocardial blood flow (MBF) were determined under basal conditions, during dobutamine infusion (DOB: 20 microg x kg(-1) x min(-1) iv), and during coronary stenosis + DOB + 2-deoxyglucose (2-DG) infusion. DOB increased rate pressure products (RPP) and MBF significantly without affecting the subendocardial-to-subepicardial blood flow ratio (ENDO/EPI) or HEP levels. During coronary stenosis + DOB + 2-DG infusion, RPP, ischemic zone (IZ) MBF, and ENDO/EPI decreased significantly. The IZ ratio of creatine phosphate-to-ATP decreased significantly [2.30 +/- 0.14, 2.06 +/- 0.13, and 2.04 +/- 0.11 to 1.77 +/- 0.12, 1.70 +/- 0.11, and 1.72 +/- 0.12 for EPI, midmyocardial (MID), and ENDO, respectively], and 2-DGP accumulated in all layers, as evidenced by the 2-DGP/PCr (0.55 +/- 0.12, 0.52 +/- 0.10, and 0.37 +/- 0.08 for EPI, MID, and ENDO, respectively; P < 0.05, EPI > ENDO). In the IZ the wet weight-to-dry weight ratio was significantly increased compared with the normal zone (5.9 +/- 0.5 vs. 4.4 +/- 0.4; P < 0.05). Thus, in the stenotic perfused bed, during dobutamine-induced high cardiac work state, despite higher blood flow, the subepicardial layers showed the greater metabolic changes characterized by a shift toward higher carbohydrate metabolism, suggesting that a homeostatic response to high-cardiac work state is characterized by more glucose utilization in energy metabolism.

• Authors: Mohammad N Jameel, Xiaohong Wang, Marcel H J Eijgelshoven, Abdul Mansoor, Jianyi Zhang
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 294 Issue 6 Pg. H2680-6 (Jun 2008) ISSN: 0363-6135 [Print] United States
• PMID: 18424629 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Phosphocreatine
• Lactic Acid
• 2-deoxyglucose-6-phosphate
• Dobutamine
• Glucose-6-Phosphate
• Adenosine Triphosphate

Topics

• Adenosine Triphosphate (metabolism)
• Animals
• Coronary Circulation
• Coronary Stenosis (complications, metabolism, physiopathology)
• Disease Models, Animal
• Dobutamine
• Dogs
• Endocardium (metabolism)
• Energy Metabolism
• Glucose-6-Phosphate (analogs & derivatives, metabolism)
• Glycolysis
• Hemodynamics
• Lactic Acid (metabolism)
• Magnetic Resonance Spectroscopy
• Myocardial Ischemia (chemically induced, etiology, metabolism, physiopathology)
• Myocardium (metabolism, pathology)
• Oxygen Consumption
• Pericardium (metabolism)
• Phosphocreatine (metabolism)