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Early presence of phospholamban in developing a chick heart
Insights
Cardiac sarcoplasmic reticulum Ca2+ transport and phospholamban phosphorylation change during chick development. Separate genetic control is indicated for phospholamban and Ca2+-ATPase synthesis.
Area of Science:
- Cardiovascular physiology
- Molecular cardiology
- Developmental biology
Background:
- Phospholamban regulates sarcoplasmic reticulum Ca2+-ATPase activity in cardiac muscle.
- Understanding the developmental regulation of calcium handling is crucial for cardiac function.
Purpose of the Study:
- To investigate the developmental changes in phospholamban phosphorylation and sarcoplasmic reticulum Ca2+ transport in embryonic and post-hatch chick hearts.
- To explore the relationship between phospholamban and Ca2+-ATPase during cardiac development.
Main Methods:
- Crude membrane preparations from embryonic, newborn, and adult chick hearts were utilized.
- Maximal phosphorylation of phospholamban by cyclic AMP-dependent protein kinase was measured.
- Active Ca2+-uptake into sarcoplasmic reticulum vesicles was assessed.
Main Results:
- Phospholamban phosphorylation increased from embryonic day 4 to 15, then decreased with further development.
- Active Ca2+-uptake rose from day 4-7, with a significant increase around hatching.
- Ca2+-transport activity showed a substantial rise at the time of hatching.
Conclusions:
- Phospholamban phosphorylation and sarcoplasmic reticulum Ca2+ transport exhibit distinct developmental patterns in the chick heart.
- The data suggest independent genetic regulation of phospholamban and sarcoplasmic reticulum Ca2+-ATPase synthesis.
Abstract:
Phosphorylation of phospholamban and development of reticular Ca2+ transport were studied in crude membrane preparations of embryonic, newborn and adult chick heart. Maximal phosphorylation of phospholamban by added catalytic subunit of cyclic AMP-dependent protein kinase increases from embryonic day 4-15. It decreases with further development. In the same membrane preparations active Ca2+-uptake into vesicles of sarcoplasmic reticulum rises from day 4-7 and decreases then slightly until day 20. A several-fold increase in Ca2+-transport activity occurs at the time of hatching. The data indicate separate genetic control for synthesis of phospholamban and sarcoplasmic reticulum Ca2+-ATPase.