SOURCES OF ERRORS IN DIFFERENT SINGLE-ELECTRODE VOLTAGE-CLAMP TECHNIQUES - A COMPUTER-SIMULATION STUDY

The use of voltage clamp with a single electrode has been useful in es timating kinetic parameters for a number of ionic whole-cell currents. There are two main types of such a technique: discontinuous voltage c lamp (dSEVC) (Brennecke and Lindemann, 1974), and continuous voltage c lamp (cSEVC) (Hamill et al., 1981). We have studied, by means of compu ter simulations, the performance of both types of clamp on estimating activation kinetics parameters of a typical neuronal Ca2+ current. Dev iations from the theoretical values are shown to be sensitive on both set-up and cell properties. Both types of clamp are shown to lose volt age control when either access resistance or absolute membrane conduct ance are increased. In contrast, changes in membrane capacitance affec t differently to the estimates obtained by the two types of clamp. Cel l size is also shown to affect cSEVC performance but not that of dSEVC . The nature and magnitude of errors obtained by using both types of c lamp in different situations are discussed.