Transmural triglycerides in acute myocardial ischaemia

Area of Science:

• Cardiovascular Physiology
• Biochemistry
• Pharmacology

Background:

• Endogenous triglycerides are crucial energy substrates for the heart.
• Understanding their metabolic fate during ischemia is vital for cardiac health.
• Left ventricular subepicardium and subendocardium exhibit distinct metabolic properties.

Purpose of the Study:

• To investigate the dynamic changes in endogenous triglycerides within the left ventricular subepicardium and subendocardium following acute coronary artery occlusion.
• To determine the impact of beta-blockers on these triglyceride alterations during ischemia.

Main Methods:

• Open-chest anesthetized dog model.
• Acute coronary artery occlusion induced surgically.
• Measurement of triglyceride concentrations in subepicardial and subendocardial tissues at various time points post-occlusion.
• Administration of propranolol or bevantolol prior to occlusion.

Main Results:

• Subepicardium had higher baseline triglyceride levels than subendocardium.
• Ischemic subepicardial triglycerides decreased initially, then increased significantly from 60 to 240 minutes post-occlusion.
• No significant changes in subendocardial triglycerides were observed in either normal or ischemic regions.
• Beta-blockers (propranolol, bevantolol) prevented the initial decrease in subepicardial triglycerides.

Conclusions:

• Coronary artery ligation induces a biphasic response in transmural endogenous triglycerides.
• The initial phase involves triglyceride mobilization, followed by deposition in the ischemic subepicardium.
• Beta-1 adrenergic receptor blockade influences triglyceride metabolism during myocardial ischemia.