Mechanosensitive cation channels in human leukaemia cells: calcium permeation and blocking effect

摘要: Cell-attached and inside-out patch-clamp methods were employed to identify characterize mechanosensitive (MS) ionic channels in the plasma membrane of human myeloid leukaemia K562 cells. A reversible activation gadolinium-blockable mechanogated currents response negative pressure application was found 58 % stable patches (n = 317). I-V relationships measured with a sodium-containing pipette solution showed slight inward rectification. Data analysis revealed presence two different populations that distinguishable by their conductance properties (17.2 +/- 0.3 pS 24.5 0.5 pS), but indistinguishable regard selective pharmacological properties. Ion-substitution experiments indicated MS cells permeable cations not anions do discriminate between Na(+) K(+). The fully impermeable large organic such as Tris(+) N-methyl-D-glucamine ions (NMDG(+)). Ca(2+) permeation blockade examined using pipettes containing concentrations Ca(2+). In 2 mM CaCl(2), when other impermeant, both outward single-channel observed; relationship unitary 7.7 1.0 pS. relative permeability value, P(Ca)/P(K), equal 0.75, estimated at physiological concentrations. Partial or full inhibition through observed higher external (10 20 mM). No activated 90 CaCl(2). Monovalent significantly affected extracellular within range (0-2 mM), some