How does the heart use fatty acids for energy?

The heart utilizes fatty acids as a major fuel source through a process involving uptake, activation, and subsequent metabolism. Here's a breakdown:

Fatty Acid Uptake and Activation

The initial step involves the heart muscle cells (cardiac myocytes) taking up fatty acids. This occurs through two main mechanisms:

• Diffusion: Fatty acids can passively diffuse across the cell membrane.
• Transporters: Specific proteins, such as CD36 and FATP transporters, facilitate the movement of fatty acids across the cell membrane.

Once inside the cell's cytosol, fatty acids are bound to fatty acid binding proteins and must be "activated". This activation process involves:

1. Esterification: Fatty acids are esterified to fatty acyl CoA.
2. Enzyme: This reaction is catalyzed by fatty acyl CoA synthase (FACS).

This forms fatty acyl-CoA, which is a crucial intermediate for further metabolism.

Subsequent Metabolism (Beyond the Reference)

Although the provided reference focuses on the initial uptake and activation, here's what happens next for a complete picture:

• Transport into Mitochondria: Fatty acyl-CoA is transported into the mitochondria, the cell's power plants, for beta-oxidation.
• Beta-Oxidation: In beta-oxidation, fatty acyl-CoA is broken down into acetyl-CoA molecules.
• Citric Acid Cycle (Krebs Cycle): Acetyl-CoA enters the citric acid cycle, generating high-energy molecules like NADH and FADH2.
• Electron Transport Chain: NADH and FADH2 donate electrons to the electron transport chain, ultimately leading to the production of ATP (adenosine triphosphate), the heart's primary energy currency.

Summary