The intracellular distribution of calcium.

For a long time, the study of calcium distribution in neurons was plagued by artifacts and technological problems. Major progress in the field has now been made using a variety of techniques, such as electronprobe X-ray microanalysis of unfixed, rapidly frozen sections, subcellular fractionation and cell permeabilization, and by recently introduced indirect approaches ([Ca2+]i topology revealed by fluorescent dyes and photoproteins; immunocytochemistry of Ca2+-binding proteins). The present interest is focused primarily on rapidly exchanging Ca2+ pools that are responsible for the generation of [Ca2+]i transients. These pools might reside in organelles (calciosomes and possibly others) indistinguishable by conventional EM, but molecularly and functionally distinct from the elements of the smooth endoplasmic reticulum (SER). © 1988.