N-methyl-D-aspartate-activated channels of mouse central neurones in magnesium-free solutions.

摘要: 1. The whole-cell and outside-out configurations of the patch-clamp method were used to investigate properties channels activated by N-methyl-D-aspartate (NMDA channels) in mouse central neurones culture. Recording was made Mg2+-free solutions. 2. In recording mode currents induced both NMDA L-glutamate accompanied a large increase noise. cases noise power spectra well fitted single Lorentzian functions corresponding mean time constant, tau, about 6 ms at room temperature. single-channel conductance, gamma n, estimated from ratio variance total current, varied between 22 40 pS. 3. Endogenous amino acids known activate receptors (L-glutamate, L-aspartate, L-cysteine sulphinate quinolinate) as exogenous agonists such ibotenate trans-2,3-piperidine dicarboxylate (trans-PDA) all produced similar responses. particular, analysis current yielded tau values 4 8 cases. 4. responses antagonized 2-amino-5-phosphonovalerate (APV) without any effect on n or measured analysis; also diminished D-alpha-aminoadipate cis-2,3-piperidine dicarboxylate. 5. patches, it observed that amplitude varies linearly function membrane potential -80 +60 mV. reversal is near 0 are permeable Na+, K+ Cs+, but blocked choline. e, 50 pS 6. open bursts short openings interrupted brief closures. At -60 mV, closures had duration, tc, 0.4 +/- 0.2 ms. channel time, to, 5.9 1.0 for 5.3 1.7 L-glutamate. burst tb, 10.5 0.7 8.5 2.0 7. When temperature increased 14 24 degrees C, conductance with Q10 1.6 while decreased close 8. showed, addition 'main' state (40-50 pS), smaller states 15 35 pS.(ABSTRACT TRUNCATED AT 400 WORDS)