Biochemistry of the heart Quiz

Lipid Organization and Genetic Disorders

• Tafazzin is responsible for organizing inner mitochondrial membrane lipids and proteins.
• Defects in the taffazin gene are associated with Barth syndrome.
• Barth syndrome is primarily characterized by cardiomyopathy and skeletal myopathy.

Autoimmune Disorders and Cardiolipin

• The autoimmune disorder characterized by the production of antibodies that react with cardiolipin is Antiphospholipid Syndrome.
• Cardiolipin is a phospholipid abundant in the heart, synthesized in mitochondria.
• The structure of mature cardiolipin is a tetra-acyl phospholipid.

Cardiovascular System and Oxidative Stress

• The primary effect of oxidative stress on the cardiovascular system is increased cardiovascular risk.
• Advanced Glycation End-Products (AGEs) are proteins or lipids that have become non-enzymatically glycosylated, contributing to oxidative stress.
• AGEs are related to cardiovascular complications, such as atherosclerosis and diabetic cardiovascular disease.

Biomarkers and Cardiovascular Effects

• The preferred biomarker to detect myocardial injury is Troponin.
• The main cardiovascular effect of aspirin is the inhibition of eicosanoid synthesis, leading to cardioprotective effects.
• Aspirin relates to eicosanoid synthesis through the inhibition of cyclooxygenase, resulting in reduced thromboxane production.
• The most common marker used to evaluate acute myocardial infarction (MI) and risk-stratification in acute coronary syndromes (ACS) is Troponin.
• The cytosolic isoform of creatine kinase used for detecting additional cardiac muscle injury over time is CK-MB.

Energy Metabolism in Cardiomyocytes

• Cardiomyocytes primarily rely on fatty acids as energy sources in the fasted state.
• When stores of glycogen are low, ATP synthesis in mitochondria decreases.
• The phosphocreatine shuttle is a mechanism that rapidly regenerates ATP in cardiomyocytes.
• The function of the phosphocreatine shuttle is to maintain ATP homeostasis during high-energy demand.

Cardiac Hypertrophy and Metabolic Adaptations

• Pathological cardiac hypertrophy is associated with a decrease in the PCr/ATP ratio.
• Metabolic adaptations in response to pressure-overload hypertrophy and dilated cardiomyopathy include increased glucose uptake and glycolysis.
• Adenosine regulates cardiac function by reducing heart rate and contractility.
• When adenosine is produced in cardiac myocytes, intracellular Ca2+ levels decrease.

Energy Metabolism Regulation

• Peroxisome proliferator-activated receptor α (PPARα) regulates cardiac metabolism by promoting fatty acid oxidation.
• The adenosine hypothesis proposes that adenosine acts as a metabolic sensor to regulate cardiac energy metabolism.
• The role of oxidative stress in cardiovascular disease is to promote inflammation and cellular damage.
• Hypoxia-inducible factor-1α (HIF-1α) is responsible for the adaptation to hypoxic and ischemic conditions in cardiac metabolism.