Calcium inward current and related charge movements in the membrane of snail neurones.

摘要: 1. Isolated and intracellularly perfused neurones from the snail Helix pomatia have been investigated under voltage-clamp conditions. Calcium inward current asymmetric displacement were examined. 2. Two components of distinguished. One them was irreversibly blocked by intracellular fluoride together with calcium current. Another component (about 20%) not affected. The relation fluoride-sensitive to activity channels investigated. 3. amounts charge displaced on- off-responses similar. maximum between 1500 2000 electron charges/micrometers 4. normalized steady-state voltage distribution curve coincided square root conductance. slope 4 mV per e-fold change for conductance 8 te distribution. Thus, effective valencies close 6 (for conductance) 3 distribution), suggesting two gating particles channel. 5. on-process fitted m2 kinetics. time constant tau m corresponded ason in a wide range tested voltages. This correspondence failed only at small depolarizations where exceeded ason. 6. 'off' constants (tau Caoff) asoff) examined -40 did depend significantly on test pulse height. ratio asoff/tau Caoff varied 1.7 2.5. 7. inward-current relaxation kinetics measured shifts membrane potential (Vtest = -2 mV) applied peaks smaller than depended weakly voltage. 8. It is concluded that related activation channels.