Recording membrane currents of peripheral neurones in short-term culture

Abstract

Abstract In comparison with central neurones, ganglion cells are attractive because they are accessible collections of relatively uniform cell types, easily identified visually. An added advantage is that they are generally large—dorsal root ganglion (DRG) cells being 10-60 μm and sympathetic superior cervical ganglion (SCG) cells being 15—40 μm—thus, they are readily accessible to electrophysiological techniques. Quite apart from questions concerning the physiology of the sensory system, the unipolar DRG and nodose ganglion cells can be viewed as model spherical neurones to which can be applied more general questions concerning pre- or post-synaptic membrane processes. They have, for example, been used extensively to examine biochemical processes governing calcium channel function. Thus, they are an invaluable electrophysiological tool from which we can gain insights into the mechanisms at work in less accessible neuronal membranes. On the other hand, SCG cells are normally multipolar, and so lack the ideal compactness afforded by the sensory ganglion cells; however, they temporarily adopt this ideal spherical form when dispersed from the ganglion. At this stage their membrane currents can be studied without the complications of dendrites. In this chapter, we concentrate on a short-term preparation or isolated cells-to be studied within 24 h-and have chosen sympathetic SCG cells as our example. The purpose of this preparation is to achieve rapid cell dissociation for electrophysiology in which high cell yield is not important (4000 cells per day is usually enough for most electro physiologists). Our emphasis is on how to optimize conditions for good control of the membrane voltage, and how to make use of this in interpreting the membrane currents seen.