マルチマイクロプロセッサによる適応的電圧クランプ法

抄録

A new method of voltage clamping of biological membranes with time-variant parameters has been developed. In our previous system, the control ability was not sufficient in the active state where the membrane showed a considerable increase of conductance. In this paper, we discuss a new multimicroprocessor system to overcome the above problem and realize fast adaptive control of biological membranes. The system was developed through four approaches as follows.
(1) Projection algorithm was applied to the parameter estimation to design the optimal time-pattern of the effective loop conductance in the negative feedback loop.
(2) Adaptive control method by iteration was design as follows: in each stage of realtime sampling, the deviation current from the preceding controlled current was controlled by voltage feedback, and the modified current was injected to the membrane in order to charge up the membrane capacitance to the command voltage. This method was repeated until the difference between the command voltage and the membrane voltage reached some minimum level.
(3) Multi-microprocessor system which had master-slave structure was developed to realize high speed sampled-data control, parallel processings of parameter estimation and display of experimental results.
(4) System performance was tested on the electronic exitable membrane model which simulated conductance changes of smooth muscle membranes.
From the experimental results of the performance test, it is concluded that the adaptive voltage clamp method is very effective in the active condition as well as steady state condition of several kinds of exitable membranes.