title: Microelectrode studies of the effect of lanthanum on the electrical potential and resistance of outer and inner cell membranes of isolated frog skin.
abstract: Microelectrodes were used to investigate the effect of 0.5 mM mucosal lanthanum (La3+) on the intracellular potential and the resistance of outer and inner isolated frog skin (Rana esculenta) cell membranes. Under short-circuit conditions, the transapical membrane potential Vsco (mean value = -65.4 +/- 3.2 mV, inside negative) hyperpolarized to -108.7 +/- 2.3 mV in control skins, after addition of the sodium blocker amiloride. Current-voltage curves for the outer and inner membranes were constructed from the amiloride-inhibitable current versus the outer membrane potential Vo or the inner membrane potential Vi. The outer, and to a lesser degree the inner, membrane showed a characteristic nonlinearity with two slope resistances. Addition of La3+ to the outer medium increased the short-circuit current to 190% of the control value. Vsco concomitantly changed to -28 +/- 3.5 mV and outer and inner membrane resistances fell, considerably attenuating the nonlinearity seen in control skins. La3+ is suggested to raise the conductance by its effect on the surface potential. A secondary long-term inhibitory effect of La3+ on short-circuit current has been observed. It is ascribed to the penetration of La3+ into the sodium channels.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D007473:Ion Channels / Q000378:metabolism; D007700:Kinetics; D007811:Lanthanum / Q000502:physiology*; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D011893:Rana esculenta; D012879:Skin Physiological Phenomena; D012964:Sodium / Q000378:metabolism
chemical_list: D007473:Ion Channels; D007811:Lanthanum; D012964:Sodium