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[Metabolism of myocardial poly A+-containing mRNA normally and in compensatory cardiac hyperfunction]
Abstract:
Two fractions of mRNA--polyA+ and polyA- containing mRNA--were found in rat heart muscle by affinity chromatography using polyU cellulose. These fractions constituted 30% and 70% of total mRNA, respectively. The ratio of polyA+/polyA- mRNA was not altered in myocardium under heart hyperfunction and in physiological ageing. Duration of life of polyA+ containing mRNA was 4 hrs in normal heart. A; the beginning of myocardium hyperfunction the period of mRNA life was decreased down to 2-3 hrs; this pattern of mRNA life alteration did not differ from control one in prolonged heart hypertrophy within 6 months. The rate of polyA+ containing mRNA synthesis was increased by 70% at the early steps of heart hyperfunction as compared with normal state; it decreased below the normal state in long-term hypertrophy of myocardium. In development of heart hyperfunction acceleration of polyA+ containing mRNA synthesis was more distinct than an increase in rRNA synthesis.
Insights
Polyadenylated mRNA (polyA+) in rat hearts has a 4-hour lifespan, decreasing during hyperfunction. PolyA+ mRNA synthesis initially increases then declines in heart hypertrophy, impacting cardiac function.
Area of Science:
- Molecular Biology
- Cardiovascular Science
- Biochemistry
Context:
- Messenger RNA (mRNA) processing and stability are crucial for cellular function.
- Polyadenylated (polyA+) and non-polyadenylated (polyA-) mRNA fractions exist in eukaryotic cells.
- Rat heart muscle mRNA was analyzed to understand its characteristics and regulation.
Purpose:
- To investigate the characteristics and dynamics of polyA+ and polyA- mRNA in rat heart muscle.
- To determine the impact of heart hyperfunction and physiological aging on mRNA fractions.
- To analyze the synthesis rates and lifespan of polyA+ mRNA under different cardiac conditions.
Summary:
- Two mRNA fractions, polyA+ (30%) and polyA- (70%), were identified in rat heart muscle.
- The polyA+/polyA- ratio remained stable during heart hyperfunction and aging.
- PolyA+ mRNA lifespan decreased from 4 hours to 2-3 hours during early hyperfunction.
- PolyA+ mRNA synthesis increased by 70% in early hyperfunction but decreased in long-term hypertrophy.
- PolyA+ mRNA synthesis changes were more pronounced than rRNA synthesis changes during heart hyperfunction.
Impact:
- Provides insights into mRNA regulation in cardiac physiology and pathology.
- Highlights the dynamic changes in mRNA metabolism during heart stress.
- Suggests specific molecular mechanisms underlying cardiac adaptation and dysfunction.