ATP-sensitive K+ and Ca2+-activated K+ channels in lamprey ( Petromyzon marinus) red blood cell membrane.
The patch-clamp technique was used to demonstrate the presence of ATP-sensitive K(+) channels and Ca(2+)-activated K(+) channels in lamprey ( Petromyzon marinus) red blood cell membrane. Whole-cell experiments indicated that the membrane current under isosmotic (285 mosmol l(-1)) conditions is carried by K(+). In the inside-out configuration an ATP-sensitive K(+) channel (70-80 pS inward, 35-40 pS outward) was present in 35% of patches. Application of ATP to the intracellular side reduced unitary current with half-maximal inhibition in the range 10-100 microM. A block was obtained with 100 microM lidocaine and inhibition was obtained with 0.5 mM barium acetate. A Ca(2+)-activated K(+) channel (25-30 pS inward, 10-15 pS outward) was present in 57% of patches. Inhibition was produced by 10 mM TEA and 500 nM apamin and sensitivity to Ba(2+) was lower than for ATP-sensitive channels. No spontaneous channel activity was recorded in the cell-attached configuration under isotonic conditions. With hypotonic saline 68% of patches showed spontaneous single-channel activity, and, of 75 active patches, 66 cell-attached patches showed channel activity corresponding to Ca(2+)-activated K(+) channels.
Lapaix
Franck
F
Centre National de la Recherche Scientifique, UPR 9042, Station Biologique, Place GTeissier, BP74, 29682 Roscoff cedex, France.
Egée
Stéphane
S
Gibert
Lionel
L
Decherf
Gaëtan
G
Thomas
Serge L Y
SL
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D004553:Electric Conductivity; D004910:Erythrocyte Membrane / Q000378:metabolism*; D007038:Hypotonic Solutions / Q000494:pharmacology; D007798:Lampreys / Q000097:blood*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000494:pharmacology*; D024681:Potassium Channels, Calcium-Activated / Q000097:blood* / Q000502:physiology; D024661:Potassium Channels, Inwardly Rectifying / Q000097:blood* / Q000187:drug effects / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology
D007038:Hypotonic Solutions; D024681:Potassium Channels, Calcium-Activated; D024661:Potassium Channels, Inwardly Rectifying; D012965:Sodium Chloride; D000255:Adenosine Triphosphate; D011188:Potassium