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High sensitivity of cultured cardiac muscle cells to autonomic agents
Abstract:
We have established conditions under which cultured embryonic myocardial cells are highly sensitive to the autonomic agents norepinephrine and acetylcholine and have determined that the most important factors affecting this sensitivity involve the application protocol. Using cells 3-5 days in culture, isolated from ventricles of 13-day chick embryos, the ED50 for noerpinephrine was 800 pM and that for acetylcholine was 370 pM. These cells were more than 2 orders of magnitude more sensitive than 13-day embryonic hearts freshly isolated, but not dispersed. Intracellular recording of the membrane actions of norepinephrine and acetylcholine on these cultured cells showed changes in pacemaker slope similar to those seen in freshly isolated hearts. These data demonstrate that preparation of ventricular muscle as isolated cells in culture does not necessarily result in the loss of sensitivity to autonomic agents. On the contrary, the isolated cells show the highest sensitivity to norepinephrine and acetylcholine that has been reported for the myocardium.
Insights
Cultured embryonic myocardial cells exhibit heightened sensitivity to autonomic agents like norepinephrine and acetylcholine. This study reveals optimal conditions for maximizing this sensitivity in cardiac cell research.
Area of Science:
- Cardiology
- Cell Biology
- Pharmacology
Background:
- Autonomic agents modulate cardiac function.
- Understanding cellular sensitivity is crucial for cardiac research.
- Previous studies suggested potential loss of sensitivity in cultured cardiac cells.
Purpose of the Study:
- To establish conditions for high sensitivity of cultured embryonic myocardial cells to autonomic agents.
- To determine factors influencing this sensitivity, particularly application protocols.
- To compare the sensitivity of cultured cells with freshly isolated embryonic hearts.
Main Methods:
- Culturing embryonic chick ventricular cells (3-5 days in vitro).
- Administering norepinephrine and acetylcholine to assess dose-response.
- Utilizing intracellular recordings to analyze membrane potential changes.
- Comparing sensitivity metrics (ED50) between cultured and freshly isolated cells.
Main Results:
- Cultured cells showed high sensitivity to norepinephrine (ED50 = 800 pM) and acetylcholine (ED50 = 370 pM).
- Sensitivity was over 100 times greater than in freshly isolated, non-dispersed embryonic hearts.
- Observed membrane potential changes in cultured cells mimicked those in freshly isolated hearts.
Conclusions:
- Cellular preparation as isolated cultures does not inherently diminish autonomic agent sensitivity.
- Cultured embryonic myocardial cells demonstrate unprecedented sensitivity to norepinephrine and acetylcholine.
- Optimized culture conditions can yield superior models for studying cardiac autonomic pharmacology.