Journalartikel

Jahr der Veröffentlichung: 2000

Seiten: 363-369

Zeitschrift: Pflügers Archiv European Journal of Physiology

Bandnummer: 439

Heftnummer: 3

ISSN: 0031-6768

DOI Link: https://doi.org/10.1007/s004240050951

Verlag: Springer

Abstract: 
The activation of cation channels in oocytes of Xenopus laevis by the marine poison maitotoxin (MTX) was monitored as membrane current (I-m), conductance (G(m)) and membrane surface area determined by continuous measurements of membrane capacitance (C-m). When MTX (25 pM) was added to the bathing solution there was an abrupt, large increase in inward membrane currents. Current/voltage relationships (I/V curves) were linear and suggested activation of voltage-independent nonselective cation channels (NSCC). MTX-induced Ca2+- sensitive currents were mainly carried by Na+ and were suppressed by low (0 mM) or high (40 mM) external Ca2+ concentrations and removal of Na+. Gadolinium (Gd3+, 10-500 mu M) also had inhibitory effects, demonstrating the possible involvement of stretch-activated cation channels (SACC), In a high concentration (500 mu M), amiloride substantially reduced the MTX-activated current while lower amiloride concentrations (50-100 mu M) stimulated the current further. Continuous measurements of C-m revealed that MTX induced exocytotic delivery and functional insertion of new channel proteins into the plasma membrane, indicated by a Ca2+-dependent increase in membrane surface area by around 28%. From these data we conclude that MTX activates NSCC that require relatively high concentrations of amiloride to be blocked. Furthermore, MTX possibly stimulates activation of Gd3+- and Ca2+-sensitive mechanosensitive cation channels. Stimulation of these channels is achieved by exocytotic delivery and functional insertion of new channels into the plasma membrane in a pathway that depends on the presence of extracellular Ca2+.

Harvard-Zitierstil: Weber, W., Popp, C., Clauss, W. and Van Driessche, W. (2000) Maitotoxin induces insertion of different ion channels into the Xenopus oocyte plasma membrane via Ca²⁺-stimulated exocytosis, Pflügers Archiv European Journal of Physiology, 439(3), pp. 363-369. https://doi.org/10.1007/s004240050951

APA-Zitierstil: Weber, W., Popp, C., Clauss, W., & Van Driessche, W. (2000). Maitotoxin induces insertion of different ion channels into the Xenopus oocyte plasma membrane via Ca²⁺-stimulated exocytosis. Pflügers Archiv European Journal of Physiology. 439(3), 363-369. https://doi.org/10.1007/s004240050951