Publications by authors named "Weintraut H"
To investigate whether multiple peptide transporters mediate absorption of beta-lactams carrying different charges at physiological pH, we used the human intestinal cell line Caco-2 and Xenopus laevis oocytes expressing the cloned rabbit intestinal peptide transporter PepT1. Characteristics of transport of the anionic cefixime and the zwitterionic cefadroxil were assessed by 1) flux studies using radiolabeled compounds, by 2) measuring changes in pHin in cells and oocytes as a consequence of substrate-mediated proton influx and 3) by applying the two-electrode voltage clamp technique to assess the electrophysiological phenomena associated with beta-lactam transport in oocytes expressing PepT1. Both beta-lactams were rapidly taken up into Caco-2 cells and oocytes expressing PepT1 by a pH-dependent and saturable transport pathway.
View Article and Find Full Text PDFUsing Fura-2 digital imaging microscopy, we found two cell populations in chick embryo heart with different resting intracellular calcium concentration ([Ca2+]i). Electrical stimulation of the cells led to the same increase in [Ca2+]i in both cell types, e.g.
View Article and Find Full Text PDFArticle Synopsis
- The study used digital imaging microscopy and a sodium-sensitive fluorescent indicator to measure free sodium ion concentration in individual chick-embryo heart cells.
- Despite finding a consistent sodium ion concentration within each cell, there was significant variation between different cells, with levels ranging from 3 to 18 mM.
- The research also revealed a biphasic response to the drug ouabain, indicating variability in how the cells respond to this cardiac glycoside, similar to previous findings on calcium ion sensitivity in these cells.
The regulation of the intracellular sodium ion concentration in cultured chick embryo heart cells.
Biochem Biophys Res Commun
July 1992
Article Synopsis
- Researchers used digital imaging microscopy to study sodium ion concentration in chick embryo heart cells using a specific fluorescent indicator.
- Inhibiting certain sodium and calcium exchangers did not affect sodium levels, indicating those pathways aren't crucial for [Na+]i changes.
- The opening of sodium channels and inhibition of the Na(+)-K(+)-Cl(-) cotransporter significantly increased [Na+]i, highlighting their primary role in regulating sodium concentrations in these cells.
Article Synopsis
- Researchers studied cell cultures from 10-day-old chick embryo hearts and identified two distinct cell populations based on intracellular calcium concentration: high [Ca2+]i (116 nM) and low [Ca2+]i (46 nM).
- The proportion of high [Ca2+]i cells fluctuated between 10% to 60% depending on cell density, and histochemical stains indicated that the two populations did not represent muscle versus non-muscle cells.
- Exposure to ouabain revealed that high [Ca2+]i cells had a lower sensitivity to increasing [Ca2+]i compared to low [Ca2+]i cells, which showed excessive calcium increase and sensitivity to toxic ouabain concentrations.
Digital-imaging fluorescence microscopy with fura-2 allows the determination of intracellular calcium concentration ([Ca2+]i) in single cells. At a cell density of 10(5) cells/petri dish 44% of the chick embryo heart cells had a high [Ca2+]i of 99.4 +/- 7.
View Article and Find Full Text PDF