Membrane Watching

Several things, that were not all of my own choosing, have conspired to keep me out of active participation in membrane events for a while. But the spectator sport that I call "membrane watching" is far from dull. It may be as rewarding as such things as birds, Congress, girls, bali games, or the Berkeley campus-particularly when you feel yourself somewhat qualified. Of course you lose the tremendous reward of that first glimpse of the unknown, and you are without much of the solid foundation and expertise of the professional specialist. But you can skim the excitement from dozens of workers without all their frustrating drudgery, and you can flex your muscles, even grunt, to help them along. As to the background, much of the present excitement stems from the North Atlantic squid and its giant axon which Young (1) promoted 30 yr ago. But thls lovely beast has only just now been fairly shown to the public by the National Geographic (2). By Pearl Harbor, the membrane of this half-millimeter axon was described as an electrical capacity (3) with some conductance (4). The capacity was quite constant and independent of spectacular changes in the conductance (5). So the capacity G, Fig. 1 has mostly been left for others to struggle with, and progress has been slow. Whereas a Debye dielectric dispersion behaved as 1 or i~or, many solids followed the empirical relation (6) 1 or (io~r) ~. But then, with some theoretical basis, there were liquids which behaved (7) according to (1 or io~r)o, and now a large number of polymers are well described (8) by [1 or (io~r)~] n. Explanations may be slow in coming and may not be much help for cell membranes. We can watch and hope, but for them we only know a high-frequency approximation (9) (i~0r)v. T membrane impedance measurements which gave basis for some other subthreshold phenomena. The membrane conduction current, Fig. 1, which seemed certain to be ionic, was highly nonlinear in steady state (9) and showed an amazing inductive behavior (10). An explanation on the basis of electrodiffusion (I 1) of potassium, Fig. 2, was successful enough (12) to be very attractive for a long time. The subthreshold data were later fully confirmed and carefully described in terms of potassium (13) but we have seen the electrodiffusion theory become quite feeble over the quarter century (14). However, we traced the ion …