title: The effect of extracellular Ca and Mg on mitochondrial ultrastructure in isolated intact neurons.
abstract: The ultrastructural transformations of mitochondria in isolated crayfish neurons were studied after incubation of the cells in saline media containing different Ca2+ and Mg2+ concentrations. Incubation in a 5-fold higher Ca concentration resulted in the swelling of mitochondria that was prevented by the addition of the calcium channel blocker, verapamil. Exposure of the cells to Mg2+-depleted medium induced swelling of all the mitochondria, followed by substantial shrinkage of most of them. The absence of Ca as well as the presence of verapamil in Mg2+-free medium led to the inhibition of mitochondrial swelling and to a strong contraction of the mitochondria after 1 h incubation. The omission of Ca2+ from the saline medium or the addition of Ca2+-ionophore A23187 in the presence of Ca2+ resulted in strong mitochondrial shrinkage. These structural alterations of mitochondria are interpreted as an osmotic response of the inner mitochondrial membranes to changes in their potassium transport, induced by a disturbance in the cellular and mitochondrial Ca2+-Mg2+ homeostasis.
mesh_terms: D000818:Animals; D003400:Astacoidea; D002118:Calcium / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology*; D008854:Microscopy, Electron; D008928:Mitochondria / Q000187:drug effects / Q000648:ultrastructure*; D009474:Neurons / Q000187:drug effects / Q000648:ultrastructure*
chemical_list: D008274:Magnesium; D002118:Calcium