A non-selective cation channel in the apical membrane of cultured A6 kidney cells.
The patch-voltage clamp technique was used to investigate the characteristics of a non-selective cation channel (NSCC) identified in the apical membrane of cultured A6 toad kidney cells. The NSCC was present in cell-attached and inside-out membrane patches. The characteristics of this NSCC are as follows: (a) linear current-voltage relationship with a channel conductance of 21 +/- 2 pS; (b) a low selectivity between Na+ and K+ (1.5:1); (c) a high selectivity of Na+ to Cl- (greater than 45:1); (d) this channel has a single open state and two closed states; (e) the open-time constant and the second closed-time constant of this channel are voltage dependent; and (f) this NSCC is insensitive to amiloride (10(-7) M). We conclude that the NSCC resembles previously described non-selective cation channels. The NSCC of the apical membrane of A6 cells may aid in the movement of Na+ and K+ in response to varying ionic concentrations across the apical membrane.
Department of Physiology and Biophysics, University of Alabama, Birmingham.
K L
KL
Hamilton
D J
DJ
Benos
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002025:Bufonidae; D002412:Cations; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism; D004553:Electric Conductivity; D007473:Ion Channels / Q000502:physiology*; D007668:Kidney; D007700:Kinetics; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D002412:Cations; D002712:Chlorides; D007473:Ion Channels; D000584:Amiloride; D012964:Sodium; D011188:Potassium