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Enzymes involved in guanine monophosphate metabolism of aging chicken heart
1Institute of Histology and General Embryology, University of Bologna, Italy.
Insights
Enzymes regulating guanosine monophosphate (GMP) metabolism shift pathways during aging in chicken hearts. Young chickens favor salvage, while aged chickens utilize salvage more to maintain guanine nucleotide pools.
Area of Science:
- Biochemistry
- Gerontology
- Cardiovascular Physiology
Background:
- Guanosine monophosphate (GMP) is a crucial purine nucleotide.
- Understanding GMP metabolism is vital for comprehending cellular energy and aging processes.
- Enzyme activity in purine metabolism changes with age, impacting nucleotide pools.
Purpose of the Study:
- To investigate the age-related changes in enzyme activities governing GMP metabolism in chicken hearts.
- To elucidate the temporal regulation of purine pathways during cardiac aging.
- To determine how GMP metabolism shifts contribute to nucleotide pool maintenance in aging hearts.
Main Methods:
- Enzyme activity assays were performed on heart tissue from chickens at different age points (1-day, 20-day, 12-month, 30-month).
- Key enzymes in GMP breakdown (catabolism) and salvage pathways were quantified.
- Activity levels were correlated with age to identify metabolic shifts.
Main Results:
- In newborns, GMP breakdown is dominant; the salvage enzyme hypoxanthine-guanine phosphoribosyl-transferase (HGPRT) is undetectable.
- Young chickens exhibit maximal HGPRT activity and low xanthine oxidase, indicating a shift towards the salvage pathway.
- Adult hearts show maximal catabolic enzyme activity, while aged hearts display reduced catabolism and increased salvage pathway utilization.
Conclusions:
- GMP metabolism in the aging chicken heart demonstrates a temporal regulation of purine pathways.
- A shift towards the salvage pathway in aged hearts may be essential for maintaining the guanine nucleotide pool.
- These findings suggest a coordinated age-dependent adaptation in purine metabolism within the cardiac tissue.
Abstract:
The activities of enzymes involved in GMP metabolism were studied in the heart of aging chickens. In newborn (1-day-old) animals, GMP breakdown apparently leads to the final products of purine metabolism, as the activity of hypoxanthine-guanine phosphoribosyl-transferase (HGPRT), the salvage enzyme of GMP is not detectable. On the contrary, HGPRT shows maximal activity in young (20-day-old) chickens, when xanthine oxidase activity is very low, indicating that the metabolic flux converges on the salvage pathway. Again, maximal activity of the catabolic enzymes and a limited resort to the salvage pathway characterize GMP metabolism of adult (12-month-old) hearts. Finally, in aged (30-month-old) chickens, a reduced GMP catabolism and a greater utilization of the salvage pathway might contribute to the maintenance of the guanine nucleotide pool. In conclusion, the pattern of the activities of enzymes relating to GMP metabolism in the aging heart, compared to AMP metabolism, indicates a parallel temporal regulation of the purine pathways.