Craig C. Freudenrich

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Cytosolic free magnesium concentration [Mg2+]i and its regulation were studied in cultured embryonic chicken heart cells by use of the fluorescent indicator 2-[2-(5-carboxy)oxazole]-5-hydroxy-6-aminobenzofuran-N,N,O-triacet ic acid (Furaptra). The intracellular location of Furaptra was confirmed by its complete release from cells upon addition of saponin.(More)
To assess the role of pH in cellular Mg homeostasis, cytosolic pH (pHi) was manipulated by the NH4Cl prepulse technique; pHi, cytosolic Mg2+ (Mgi), and cytosolic Ca2+ (Cai) were measured fluorometrically in single cultured embryonic chicken heart cells loaded with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF), FURAPTRA, and fura-2, respectively.(More)
Several aspects of Mg2+ homeostasis were investigated in cultured chicken heart cells using the fluorescent Mg2+ indicator, FURAPTRA. The concentration of cytosolic Mg2+ ([Mg2+]i) is 0.48 ± 0.03 mM (n = 31). To test whether a putative Na/Mg exchange mechanism controls [Mg2+]i below electrochemical equilibrium, we manipulated the Na+ gradient and assessed(More)
The effect of anoxia and substrate removal on cytosolic free calcium (Ca2+i), cell calcium, ATP content, and calcium efflux was determined in cultured monkey kidney cells (LLC-MK2) exposed to 95% N2, 5% CO2 for 60 min. In the control period, the basal Ca2+i level was 70.8 +/- 9.4 nM. During 1 h of anoxia without substrate, ATP content decreased 70%, Ca2+i(More)
A simple method for incorporating aequorin into mammalian cells to measure cytosolic ionized Ca2+ is described and compared with scrape loading and hypoosmotic treatment (HOST). The procedure consists of incubating the cells for 10 min and centrifuging them at 200 g for 30 s in the presence of aequorin. This method incorporates the same amount of(More)
These studies were designed to examine the cellular messenger that mediates the action of angiotensin II on fluid transport (Jv) in the rabbit proximal tubule. We measured the effects of angiotensin II on Jv, activation of adenylate cyclase, and the concentration of cytosolic free calcium (Cai) in the rabbit proximal tubule. In nine rabbit proximal(More)
Calcium-free incubation followed by exposure to calcium damages naturally occurring cardiac muscle preparations irreversibly. Whether the observed calcium overload during calcium repletion is a primary cause for, or a secondary consequence of, sarcolemmal disruption and cell injury is controversial. We used cultured embryonic chicken heart muscle cells to(More)
Cell physiological and pathophysiological studies often require information about the elemental composition of intracellular organelles in situ. Electron probe X-ray microanalysis (EPXMA) is one of the few methods by which intracellular elemental content and distribution can be measured simultaneously. While several cryofixation techniques for EPXMA have(More)