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Calcium (Ca2+) is an almost universal intracellular messenger, controlling a diverse range of cellular processes, such as gene transcription, muscle contraction and cell proliferation. The ability of a simple ion such as Ca2+ to play a pivotal role in cell biology results from the facility that cells have to shape Ca2+ signals in the dimensions of space,(More)
Elementary Ca(2+) signals, such as "Ca(2+) puffs", which arise from the activation of inositol 1,4,5-trisphosphate receptors, are building blocks for local and global Ca(2+) signalling. We characterized Ca(2+) puffs in six cell types that expressed differing ratios of the three inositol 1,4,5-trisphosphate receptor isoforms. The amplitudes, spatial spreads(More)
We have used the whole cell configuration of the patch-clamp technique to investigate volume-activated Cl- currents in BC3H1 and C2C12 cells, two mouse muscle cell lines that can be switched from a proliferating to a differentiated musclelike state. Reducing the extracellular osmolality by 40% evoked large Cl- currents in proliferating BC3H1 and C2C12(More)
The role of membrane traffic in the stimulation of apical Na+ permeability caused by increases in cytoplasmic cyclic AMP was assessed by measuring the effects of forskolin on transepithelial capacitance (CT), transepithelial conductance (GT), and short-circuit current (Isc) in A6 cultured toad kidney cells. Apical water permeability was probed by recording(More)
Xestospongins, a group of macrocyclic bis-1-oxaquinolizidines isolated from the Australian sponge, Xestospongia species, are potent blockers of the inositol 1,4,5-trisphosphate (IP(3))-induced Ca2+ release in bi-directional Ca2+-flux conditions. We have now studied the effects of xestospongin C on the (45)Ca2+ uptake and the uni-directional (45)Ca2+ efflux(More)
The present study reports the effect of a reduction in the Na(+)-transport rate on cell volume. A decrease in transport rate was achieved by inhibition of the basolateral Na+/K+ pump with ouabain. Cultured A6 cell monolayers were short-circuited and exposed to ouabain at the basolateral surface. In one series of experiments, cells were impaled with(More)
1. We have measured changes in cell volume, membrane potential and ionic currents in distal nephron A6 cells following a challenge with hypotonic solutions (HTS). 2. The volume increase induced by HTS is compensated by a regulatory volume decrease (RVD), which is inhibited by both 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) and quinine. Quinine (500(More)
Calmodulin inhibits inositol 1,4,5-trisphosphate (IP3) binding to the IP3 receptor in both a Ca2+-dependent and a Ca2+-independent way. Because there are no functional data on the modulation of the IP3-induced Ca2+ release by calmodulin at various Ca2+ concentrations, we have studied how cytosolic Ca2+ and Sr2+ interfere with the effects of calmodulin on(More)
A sine wave method was used to measure transepithelial capacitance (CT) at 4.1 kHz (CHFT ). Model calculations show that CHFT reflects the equivalent capacitance of the series arrangement of apical and basolateral membrane capacitance. Cell swelling induced by reducing the basolateral osmolality from 260 to 140 mosmol/kg H2O (NaCl or sucrose removal)(More)
Fast confocal laser-scanning microscopy was used to study spatiotemporal properties of IP(3)-mediated Ca(2+) release signals in human SH-SY5Y neuroblastoma cells. [Ca(2+)](i) increases were not affected by ryanodine (30 microgM) or caffeine (10 mM) and largely insensitive to removal of external Ca(2+), indicating predominance of IP(3)-induced Ca(2+)(More)