Biomedical subjects

H Lock

Publications and source records attributed to H Lock.

4 recordsLinked to original sources

PubMed2001

Okadaic acid-sensitive activation of Maxi Cl(-) channels by triphenylethylene antioestrogens in C1300 mouse neuroblastoma cells.

1. The regulation of Maxi Cl(-) channels by 17beta-oestradiol and non-steroidal triphenylethylene antioestrogens represents a rapid, non-classical effect of these compounds. In the present study we have investigated the signalling pathways used for the regulation of Maxi Cl(-) channel activity by oestrogens and antioestrogens in C1300 neuroblastoma cells. 2. Whole-cell Maxi Cl(-) currents were readily and reversibly activated by tamoxifen, toremifene and the membrane-impermeant ethyl-bromide tamoxifen, only when applied to the extracellular medium. 3. Pre-treatment of C1300 cells with oestrogen or cAMP prevented the antioestrogen-induced activation of Maxi Cl(-) channels. The inhibitory effect of 17beta-oestradiol and cAMP was abolished by the kinase inhibitor staurosporine. 4. Current activation was unaffected by the removal of intracellular Ca(2+) and Mg(2+), but was completely abolished in the presence of okadaic acid. These results are consistent with the participation of an okadaic acid-sensitive serine/threonine protein phosphatase in the activation of Maxi Cl(-) channels. However, neither oestrogen or antioestrogen treatment modified the total activity of the two major serine/threonine phosphatases, PP1 and PP2A, in C1300 cells. 5. Although the role of these Maxi Cl(-) channels remains unknown, our findings suggest strongly that their modulation by oestrogens and antioestrogens is linked to intracellular signalling pathways.

Animals↗

PubMed2000

Contribution of the IsK (MinK) potassium channel subunit to regulatory volume decrease in murine tracheal epithelial cells.

The cell volume regulatory response following hypotonic shocks is often achieved by the coordinated activation of K(+) and Cl(-) channels. In this study, we investigate the identity of the K(+) and Cl(-) channels that mediate the regulatory volume decrease (RVD) in ciliated epithelial cells from murine trachea. RVD was inhibited by tamoxifen and 1,9-dideoxyforskolin, two agents that block swelling-activated Cl(-) channels. These data suggest that swelling-activated Cl(-) channels play an important role in cell volume regulation in murine tracheal epithelial cells. Ba(2+) and apamin, inhibitors of K(+) channels, were without effect on RVD, while tetraethylammoniun had little effect on RVD. In contrast, clofilium, an inhibitor of the KvLQT/IsK potassium channel complex potently inhibited RVD, suggesting a role for the KvLQT/IsK channel complex in cell volume regulation by tracheal epithelial cells. To investigate further the role of KvLQT/IsK channels in RVD, we used IsK knock-out mice. When exposed to hypotonic solutions, tracheal cells from IsK(+/+) mice underwent RVD, whereas cells from IsK(-/-) failed to recover their normal size. These data suggest that the IsK potassium subunit plays an important role in RVD in murine tracheal epithelial cells.

Animals↗

PubMed1999

NMR of samples containing metal foils.

By using spool configurations of a sample containing aluminum foil, in which the axis of the spool is collinear with the RF coil axis, one can obtain high-quality 13C NMR spectra of static samples of organic material attached to the aluminum foil. By combining such a spool configuration (or, alternatively, analogous samples containing equivalent amounts of fine aluminum powder) with the magic-angle hopping (MAH) technique, one can achieve a high degree of isotropic averaging of the 13C spectrum. This opens to NMR techniques the study of a variety of samples containing macroscopic pieces of metal foils, e.g., thin films deposited on metal foils and electrochemical systems with species adsorbed on metal-foil electrodes.

Aluminum↗

PubMedDate not supplied

Solid-state 29Si, 113Cd, 119Sn, and 31P NMR studies of II-IV-P2 semiconductors.

Solid-state 29Si, 113Cd, 119Sn, and 31P MAS NMR spectra are reported on a series of II-IV-P2 compounds. In favorable cases (e.g., high degree of crystallinity, low concentration of unpaired electrons), well-defined spectra, with sharp lines for each specific nearest-neighbor configuration, are observed; in such cases, expected J coupling patterns are also seen. High-resolution solid-state NMR studies of this type provide useful information on structure (disorder), doping, and electron-mediated coupling in semiconductor systems.

Cadmium↗