title: Microanalysis of calcium in nerve.
abstract: Free calcium in the range of 20--60 nM can be analyzed in single nerve fibers of the squid. Analytical methods used where: (1) the photoprotein aequorin, and (2) Arsenazo III, a dye which undergoes a spectral transformation when it interacts with Ca. The free calcium concentration of fresh squid axoplasm is 20--50 nM. Most cell calcium is buffered by organelles; only about 0.1% is ionized. Smooth endoplasmic reticulum appears to be a significant calcium buffer, and also, in some cases, the mitochondria located immediately adjacent to the membrane.
mesh_terms: D000331:Aequorin; D000818:Animals; D001150:Arsenazo III; D001369:Axons / Q000032:analysis*; D002118:Calcium / Q000032:analysis*; D003593:Cytoplasm / Q000032:analysis; D049832:Decapodiformes; D004721:Endoplasmic Reticulum / Q000502:physiology; D008928:Mitochondria / Q000502:physiology; D013053:Spectrophotometry
chemical_list: D001150:Arsenazo III; D000331:Aequorin; D002118:Calcium