Journal of Neurophysiology, Vol 40, Issue 2 244-259, Copyright © 1977 by APS

ARTICLES

Relationship between Muller cell responses, a local transretinal potential, and potassium flux

C. J. Karowski and L. M. Proenza

1. In the Necturus retina, light-evoked field potentials, Muller (glial) cell responses, and extracellular potassium ion concentration ([K+]0) were recorded and found to exhibit the three-way correlation characteristic of these variables elsewhere in the nervous system. 2. Muller cell responses to a flashed spot or annulus consist primarily of slow depolarizations at both light onset and offset. The responses are maximum to 0.5-mm-diameter spots and decrease with larger diameters. Responses to stimulus intensity and flicker were also used to characterize Muller cell behavior. 3. In response to long-duration stimuli, the initial Muller cell depolarization is followed by a very slow hyperpolarization, which is likely the origin of slow PIII. 4. A new extracellular potential is described, the M-wave, the basic properties of which suggest that it is generated by Muller cells. Moreover, the M-wave and Muller cells show remarkably similar behavior to a wide variety of stimulus parameters. 5. In the proximal retina, [K+]0 increases at both light onset and offset with a time course similar to that of Muller cell depolarizing responses. This K+ increase also behaves similarly to the Muller cell depolarization in response to changes in stimulus parameters. 6. It is concluded that light stimulation leads to an increase in [K+]0 in the proximal retina and that this increase depolarizes Muller cells whose associated currents, in turn, generate the M-wave.

This article has been cited by other articles:

				E. A. Newman Calcium Increases in Retinal Glial Cells Evoked by Light-Induced Neuronal Activity J. Neurosci., June 8, 2005; 25(23): 5502 - 5510. [Abstract] [Full Text] [PDF]

				C. Karwoski, H. Lu, and E. Newman Spatial buffering of light-evoked potassium increases by retinal Muller (glial) cells Science, May 5, 1989; 244(4904): 578 - 580. [Abstract] [PDF]