1. T. Takahashi, T. Tsujimoto, K. Onodera, Department of Neurophysiology, Institute for Brain Research, Faculty of Medicine, University of Tokyo, Tokyo 113, Japan.
2. I. D. Forsythe and M. Barnes-Davies, Ion Channel Group, Department of Cell Physiology and Pharmacology, University of Leicester, Post Office Box 138, Leicester LE1 9HN, UK.