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Development of acetylcholine sensitivity of embryonic chick atria in culture
Insights
Chick embryonic atria sensitivity to acetylcholine (ACh) changes with development and culture. Early embryonic atria desensitize to ACh, but factors like sera and embryo extracts can restore sensitivity.
Area of Science:
- Developmental biology
- Pharmacology
- Cardiovascular physiology
Background:
- Acetylcholine (ACh) plays a crucial role in cardiac function.
- The development of cardiac muscle sensitivity to neurotransmitters is critical for proper heart development.
- Understanding the factors influencing cardiac sensitivity to ACh in embryonic development is important.
Purpose of the Study:
- To investigate the developmental changes in chick embryonic atrial sensitivity to acetylcholine (ACh).
- To examine the effects of in vitro culture on atrial sensitivity to ACh.
- To identify factors that influence the appearance and maintenance of ACh sensitivity in embryonic hearts.
Main Methods:
- Isolation and in vitro culture of chick embryonic atria (4-12 days incubation, up to 9 days culture).
- Assessment of atrial beating response to acetylcholine (ACh) exposure.
- Investigation of the effects of sera, embryo extracts, and protein synthesis inhibitors (cycloheximide, puromycin, actinomycin D) on ACh sensitivity.
Main Results:
- Atria from early embryos (4 days) showed initial insensitivity but developed inhibition by ACh after culture.
- Atria from older embryos retained ACh sensitivity during culture.
- Sera and embryo extracts promoted ACh sensitivity, while protein synthesis inhibitors blocked its development.
- Binding of quinuclidinyl benzilate was detected even in ACh-insensitive atria.
Conclusions:
- Chick embryonic atrial sensitivity to ACh is developmentally regulated and can be modulated by culture conditions.
- The development and maintenance of ACh sensitivity require active protein synthesis.
- Factors present in sera and embryo extracts can induce or restore ACh sensitivity in embryonic cardiac tissue.
Abstract:
Atria were isolated from chick embryos of 4--12 days incubation and maintained up to 9 days in culture to examine change in their sensitivity to acetylcholine (ACh). Beating of atria from 4-day embryos was not affected by ACh at the start but was inhibited after a few days of culture. Atria from old embryos which had been sensitive to ACh remained so in culture. Desensitization to ACh was marked in short-term culture of 4-day embryonic atria. Sera and embryo extracts facilitated the appearance of ACh sensitivity. Binding of quinuclidinyl benzilate was observed in ACh-insensitive atria. Cycloheximide, puromycin and actinomycin D prevented the appearance and maintenance of ACh sensitivity in culture, leaving the heartbeat unaffected.