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Growth of the young heart: influence of nutrition and stress
Insights
Carbon monoxide (CO) exposure worsened heart enlargement in newborn rats from small litters. Litter size significantly impacts CO-induced cardiac stress, independent of anemia.
Area of Science:
- Environmental Toxicology
- Cardiovascular Physiology
- Developmental Biology
Background:
- Environmental factors and developmental conditions can influence physiological responses to toxicant exposure.
- Carbon monoxide (CO) is a known cardiovascular toxicant, but its effects can be modulated by other stressors.
- Litter size is a critical factor in early development, affecting resource availability and physiological maturation.
Purpose of the Study:
- To investigate the combined effects of carbon monoxide (CO) exposure and litter size on the developing heart in newborn rat pups.
- To determine if litter size influences the cardiac response to CO-induced stress.
- To assess the role of cellularity and anemia in mediating these effects.
Main Methods:
- Newborn rat pups were reared in litters of 4 or 16 and exposed to 500 ppm CO for 14 days or room air.
- Measurements included body weight, combined ventricle weight, hemoglobin, hematocrit, and myocardial DNA content.
- Data were analyzed to compare effects of CO exposure and litter size.
Main Results:
- CO exposure led to cardiomegaly (enlarged heart), which was more pronounced in pups from small litters (4 pups).
- Relative combined ventricle weight was not affected by litter size alone but increased with small litter size without CO stress.
- Ventricular DNA content, indicating cellularity, increased with both small litter size and CO exposure.
Conclusions:
- Small litter size exacerbates carbon monoxide-induced cardiac hypertrophy in developing rats.
- Litter size is a significant factor modulating the cardiac response to CO toxicity.
- Increased ventricular cellularity contributes to cardiac remodeling under these conditions, independent of anemia.
Abstract:
Newborn rat pups reared in litters of 4 and 16 inhaled up to 500 ppm carbon monoxide for 14 days, while others in litters of equal size remained in room air. Body weight, combined ventricle weight, hemoglobin concentration, hematocrit, and myocardial DNA content were measured. Differences in hemoglobin concentration and hematocrit between the four groups of pups were small. Cardiomegaly resulting from CO-stress was intensified in pups from small, as opposed to large litters. Relative combined ventricle weight was unaltered by change in litter size in the absence of CO-stress, although combined ventricle weight and body weight were increased with small litter size. Ventricular DNA content, indicative of cellularity, was increased in small litters and with CO-stress. Exacerbated postnatal anemia is not responsible for the differential effects of litter size and stress on the heart.