L-alanine evokes opening of single Ca2+-activated K+ channels in rat liver cells.
Cellular uptake of neutral amino acids via Na+ cotransporters is known to be associated with an increased membrane K+ conductance mediated by an unknown mechanism that is essential for avoiding excessive cell swelling. We now demonstrate by patch-clamp single-channel current recording that exposure of rat liver cells to L-alanine, but not the poorly transported D-stereoisomer, evokes opening of single K+ channels and that this effect is reversible upon removal of the amino acid. The nature of the conductance pathways opened in the intact cell by L-alanine has been investigated in cell-free excised membrane patches where it can be shown that the K+-selective channels are opened by Ca2+ acting from the inside of the membrane at a concentration as low as 0.1 microM.
D000409:Alanine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004553:Electric Conductivity; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008099:Liver / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism; D013237:Stereoisomerism
D007473:Ion Channels; D012964:Sodium; D000409:Alanine; D011188:Potassium; D002118:Calcium