Heterogenous distribution of free calcium and propagation of calcium transient in gastric parietal cells revealed by digital imaging microscopy.

Abstract

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.

Receptor-operated Ca2+ channels in gastric parietal cells: gastrin and carbachol induce Ca2+ influx in depleting intracellular Ca2+ stores

“…These results are in agreement with a previous report [41], which showed that Ins(1,4,5)P3 can partially release Ca2+ from intracellular Ca2+ stores in permeabilized parietal cells. Moreover, Tsunoda et al [43] demonstrated that in parietal cells gastrin can induce Ca2+ waves propagating within the cytosol, consistent with the existence of two different Ca2+ stores in this cell type.…”

Whole-cell K+ current activation in response to voltages and carbachol in gastric parietal cells isolated from guinea pig

“…6A). It is concluded that these currents were activated by a rise in the cytosolic free Ca 2+ concentration ([Ca2+]i); because (i) using fura-2 CCh has been shown to increase [Ca2+]i in parietal cells of a variety of animal species (Chew & Brown, 1986;Negulescu & Machen, 1988;Black et al, 1989;, including the guinea pig (Tsunoda et al, 1989; H. Tatsuta, S. Ueda & Y.…”

“…Thus, it appears that CCh induced activation of K + currents as well as nonspecific cation currents. Cytosolic Ca 2+ is known to be increased by CCh in guinea pig parietal cells (Tsunoda, Yodozawa & Tashiro, 1989). Therefore, cytosolic Ca 2+ rises may be causatively involved in CCh-induced responses.…”

Poly‐ and Monoclonal Antibodies Against Recombinant Rat Brain Calbindin D‐28K Were Produced to Map Its Selective Distribution in the Central Nervous System

“…It has been reported previously that the intracellular distribution of calcium-binding proteins may alter during development [parvalbumin (Braun et al, 1986)] or after vitamin D administration [calbindin (Taylor and Inpanbutr, 1988)l. A spatially heterogeneous subcellular distribution was also found for both free and total calcium (Chandra et al, 1989;Tsunoda et al, 1989). Tank et al (1988) were able to monitor the distributed Ca" concentration in single cerebellar Purkinje cells in a slice preparation.…”