Mouse embryonic cardiac metabolism under euglycemic and hypoglycemic conditions

Area of Science:

• Developmental Biology
• Metabolic Disorders
• Cardiovascular Science

Background:

• Infants of mothers with insulin-dependent diabetes mellitus (IDDM) exhibit a higher incidence of congenital heart defects.
• Maternal IDDM involves metabolic alterations, including frequent hypoglycemia (low blood glucose).
• Previous research suggests hypoglycemia may induce cardiac malformations in rodent embryos.

Purpose of the Study:

• To investigate the role of hypoglycemia in IDDM-related congenital heart defects.
• To determine if reduced adenosine triphosphate (ATP) production contributes to cardiac abnormalities under hypoglycemic conditions.
• To explore the metabolic pathways involved in cardiac energy production during embryogenesis.

Main Methods:

• Monitoring cardiac ATP content in rodent embryos (D10-D12) under euglycemic and hypoglycemic conditions.
• Assessing the contribution of glycolysis and the Krebs cycle to ATP production.
• Measuring cardiac lactate levels in response to altered glucose availability.

Main Results:

• Hypoglycemia did not alter the maturation of cardiac energy metabolism or deplete ATP levels.
• Cardiac ATP production shifted from glycolysis to the Krebs cycle and oxidative phosphorylation between D10 and D11.
• Hypoglycemia significantly increased cardiac lactate levels (approximately twofold) by D10.

Conclusions:

• Low ATP levels are unlikely to be the cause of hypoglycemia-induced cardiac defects in diabetic pregnancies.
• Elevated cardiac lactate levels, potentially leading to lactic acidosis, may be the underlying mechanism for heart abnormalities.
• Further research into the effects of lactic acidosis on embryonic heart development is warranted.