title: Effect of Ca-free medium on the ultrastructure and excitability of the myocardial cells of the snail, Helix pomatia L.
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium; D003470:Culture Media; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D009119:Muscle Contraction; D009206:Myocardium / Q000166:cytology*; D012908:Snails / Q000502:physiology*
chemical_list: D003470:Culture Media; D002118:Calcium