[Potassium and anion transport and activity of the Na+-pump in the erythrocyte membrane: 3 different mechanisms of regulation by intracellular calcium].
A rise in intracellular Ca2+(Ca2+in) concentration from 1 to 100 microM is accompanied by a 100-fold increase of erythrocyte membrane permeability for k+ (opening of k+-channels) as well as by membrane hyperpolarization. Both effects are partly inhibited by trifluoroperazine and completely by calmidozolium (R24571). The Ca2+-dependencies of erythrocyte permeability for K+ and of Ca2+ binding to calmodulin are in good correlation. Within the same range of Ca2+in concentrations, i.e. 1-100 microM the activity of Na+-pump decreases by 90% despite the presence of trifluoroperazine and R24571. The permeability of erythrocytes for o-phosphate anions diminishes 15-fold after addition of the anionic exchanger SITS inhibitor. The SITS-inhibited component decreases 9-10 times with a rise in Ca2+in from 10 and 100 microM. In the presence of trifluoroperazine and R24571 the sensitivity of the anionic exchanger towards Ca2+ shows a 2-3 increase. The increase in Ca2+in up to 100 microM is concomitant with the activation of 32Pi incorporation into band 4.1 protein. The effect of Ca2+in on the phosphorylation of this protein is inhibited by calmodulin inhibitors. Addition of protein kinase C activator (4 beta-phorbol-12 beta-myristate-13-acetate) also leads to the increased incorporation of 32P into band 4.1 protein, whereas protein kinase A activator (dibutyryl-cAMP) causes 32P incorporation into bands 4.1 and 5 proteins. No effect of protein kinase activators on the activity of Na+-pump as well as on the permeability of erythrocyte membranes for K+ and anions was revealed. The data obtained point to the differences in the mechanisms of Ca2+in involvement in the regulation of the above ion transport systems. Presumably, none of the mechanisms is coupled with modification of the level of cytoskeleton protein phosphorylation. The effect of Ca2+ is mediated by the Ca2+ interaction with calmodulin only in the case of K+-channels.
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000097:blood / Q000502:physiology*; D002147:Calmodulin / Q000378:metabolism; D002463:Cell Membrane Permeability; D004910:Erythrocyte Membrane / Q000378:metabolism* / Q000502:physiology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D012964:Sodium / Q000378:metabolism*
D002147:Calmodulin; D007473:Ion Channels; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000001:Calcimycin; D010042:Ouabain; D012964:Sodium; D011188:Potassium; D002118:Calcium
Transport kaliia, anionov i aktivnost' Na+-nasosa membrany éritrotsitov: tri razlichnykh mekhanizma reguliatsii vnutrikletochnym kal'tsiem.