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Perinatal nutritional modification of weanling rat heart contractile protein
Insights
Perinatal nutrition impacts adult heart enzyme activity but not calcium regulation. Litter size changes alter myosin composition, affecting cardiac contractile properties differently in weanlings versus adults.
Area of Science:
- Cardiovascular Physiology
- Developmental Biology
- Nutritional Science
Background:
- Perinatal nutritional status significantly influences organ development and function.
- Cardiac contractile proteins are crucial for heart function and are subject to developmental and environmental changes.
- Understanding how nutritional modifications affect cardiac protein properties is vital for comprehending heart health across the lifespan.
Purpose of the Study:
- To investigate the effects of litter-size-induced perinatal nutritional modifications on cardiac contractile protein enzymatic activity and isomyosin composition.
- To determine how these nutritional changes influence cardiac function from weaning to adulthood.
- To explore the relationship between thyroid hormone levels, isomyosin composition, and cardiac enzyme activities.
Main Methods:
- Litter size was adjusted to induce undernutrition or overnutrition during the perinatal period.
- Myofibrillar enzyme activities (Mg2+-ATPase, Ca2+-ATPase, creatine kinase) were measured in weanling and adult rat hearts.
- Isomyosin composition was analyzed using techniques like Hill plot analysis, and plasma thyroid hormone levels were assessed.
Main Results:
- Myofibrillar enzyme activities were unaltered in weanling hearts but significantly augmented in adult hearts following nutritional modification.
- Nutritional modification did not influence myofibrillar calcium regulation, irrespective of developmental stage.
- Undernutrition retarded and overnutrition enhanced the conversion of V3 to V1 isomyosin, while thyroid status was independent in weanlings; adult isomyosin composition remained unchanged despite increased thyroxine levels.
Conclusions:
- Perinatal nutritional modifications exert a significant influence on cardiac contractile protein enzymatic activity, particularly in adulthood.
- Isomyosin composition is sensitive to perinatal nutrition, showing altered developmental conversion patterns.
- Discrepancies between enzymatic activities, myosin composition, and heart function highlight the complex interplay of factors regulating cardiac performance during development and in response to nutritional challenges.
Abstract:
The present study ascertained the influence of litter-size-induced perinatal nutritional modification on cardiac contractile protein enzymatic activity and isomyosin composition. Myofibrillar enzyme activities for Mg2+ -ATPase, Ca2+ -ATPase, and creatine kinase (CK) in the weanling heart were unaltered by nutritional modification. However, these enzyme activities were all significantly augmented in the adult heart. Hill plot analyses of Mg2+ -ATPase activities indicated that myofibrillar calcium regulation was not influenced by either nutritional modification or the weanling-to-adult developmental progression. Isomyosin V1 composition (90 +/- 1%) correlated with plasma thyroid hormone level in normal-growth (8/litter) weanlings. Undernutrition retarded conversion of V3 isomyosin to the V1 species while overnutrition enhanced isomyosin conversion. Isomyosin composition in weanling rats subjected to perinatal nutritional modification was independent of thyroid status. In the adult rat, plasma thyroxine levels were increased, whereas V1 isomyosin remained unchanged (88 +/- 2%) compared with that of the weanling groups. Discrepancies in the relationship between contractile protein enzymatic activities, myosin composition, and heart function are apparent between both the litter-size-adjusted weanling rats and between weanling and adult animals. These discrepancies indicate the complex relationship between heart function and contractile protein properties.