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Cardiac neural crest ablation alters aortic smooth muscle force and voltage-sensitive Ca2+ responses
Christopher J Wingard1, Robert E Godt
1Department of Physiology, Medical College of Georgia, 1120 15th Street, Room CL3120, Augusta, GA 30912, USA. cwingard@mail.mcg.edu
Abstract:
Ablation of the premigratory cardiac neural crest (CNC) from the chick embryo results in a malformed outflow tract vasculature termed persistent truncus arteriosus (PTA). In addition, loss of the CNC disrupts myocardial excitation-contraction (EC) coupling, decreases intracellular Ca2+ transients, and depresses force generation. We examined if similar defects occurred in the neural crest-derived smooth muscle of the aortic arch in a test of the hypothesis that loss of elements from the CNC disrupts EC coupling and force production in the smooth muscle of the tunica media of the aortic arch. Aortic arch segments from chicks (embryonic day 15) displaying PTA generated approximately 43% of stress generated by the aortic arch from sham-operated control embryos during potassium depolarization. The depressed force response was associated with a twofold lower Fura-2 transient. In contrast, force and steady-state Fura-2 signals during endothelin-1 stimulation were unchanged. The differences seen in stress generation with potassium depolarization between sham and PTA displaying embryos were not seen in the descending aorta, a tissue not derived from the neural crest. Protein content and immunostaining revealed no differences in the content of actin, myosin, or dihydropyridine receptor from sham or PTA aortic arch. Our results suggest that the CNC is required for normal aortic arch smooth muscle function and support the hypothesis that the loss of CNC impacts the force generating ability, in part by disruption of the EC-coupling processes and altering Ca(2+)-handling.
Insights
Loss of cardiac neural crest (CNC) in chick embryos impairs aortic arch smooth muscle function. This disruption affects excitation-contraction coupling and reduces force generation, impacting vascular development.
Area of Science:
- Developmental Biology
- Cardiovascular Physiology
- Molecular Cardiology
Background:
- Premigratory cardiac neural crest (CNC) ablation in chick embryos causes persistent truncus arteriosus (PTA).
- Loss of CNC disrupts myocardial excitation-contraction (EC) coupling, reducing intracellular Ca2+ transients and force generation.
Purpose of the Study:
- To investigate if neural crest-derived smooth muscle in the aortic arch exhibits similar defects upon CNC loss.
- To test the hypothesis that CNC loss disrupts EC coupling and force production in aortic arch smooth muscle.
Main Methods:
- Aortic arch segments from chick embryos with PTA and sham-operated controls were analyzed.
- Vascular smooth muscle force generation was measured during potassium depolarization and endothelin-1 stimulation.
- Intracellular Ca2+ transients were assessed using Fura-2 imaging.
- Protein content of key contractile elements was evaluated via immunostaining.
Main Results:
- Aortic arch segments from PTA embryos generated 43% less stress than controls during potassium depolarization.
- This reduced force was linked to a twofold lower Fura-2 transient, indicating impaired Ca2+ handling.
- Force and Ca2+ signals during endothelin-1 stimulation were unaffected, suggesting specific defects in depolarization-induced responses.
- No significant differences in actin, myosin, or dihydropyridine receptor content were observed between groups.
Conclusions:
- The cardiac neural crest is essential for normal aortic arch smooth muscle function.
- Loss of CNC impairs aortic arch smooth muscle force generation, partly due to disrupted EC coupling and altered Ca2+ handling.
- These findings highlight the critical role of CNC in cardiovascular development and smooth muscle physiology.