Heterogenous distribution of free calcium and propagation of calcium transient in gastric parietal cells revealed by digital imaging microscopy.
Spatial and temporal changes of cytoplasmic free calcium concentration ([Ca2+]i) in single parietal cells of guinea pig were investigated with a digital imaging microscope equipped with a microspectrofluorometer, using a Ca2+-sensitive dye, fura-2. Intracellular distribution of [Ca2+]i was not homogeneous, but there were two kinds of [Ca2+]i gradient in the resting parietal cells, one a continuous gradient increasing towards the plasma membrane and a second discontinuous gradient (Ca2+ plateau) in some restricted regions of the cytoplasm. When treated with gastrin, only about 40% of parietal cells in the gastric gland responded with an almost twofold increase in the average resting [Ca2+]i of 52.4 +/- 7.1 nM. In the responding cells, the discontinuous plateaus transiently enlarged to the entire cytoplasm. In marked contrast, all of these cells responded to Ca2+ ionophore ionomycin. We also found that when provoked by gastrin Ca2+ transient in the parietal cells in the gastric gland often propagated to some adjacent cells, and occasionally spontaneous Ca2+ transient and oscillation were observed even in the resting state.
Tsunoda
Y
Y
Department of Physiology, Kansai Medical University, Osaka, Japan.
Yodozawa
S
S
Tashiro
Y
Y
D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004987:Ethers / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism; D005755:Gastrins / Q000494:pharmacology; D006168:Guinea Pigs; D015759:Ionomycin; D008853:Microscopy; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D001572:Benzofurans; D004987:Ethers; D005456:Fluorescent Dyes; D005755:Gastrins; D015759:Ionomycin; D002118:Calcium; D016257:Fura-2