Regenerative and passive membrane properties of isolated horizontal cells from a teleost retina

Abstract

Neurones in the intact retina are interconnected by a complex network of chemical and electrical synapses. The electrical interactions between many types of retinal neurones make it difficult to determine the active and passive membrane properties of the individual cells. A direct way to examine such properties is to dissociate the retina into single cells^1–3 and to record intracellularly from identified, isolated neurones in the absence of neural connections. Such an approach has been used to study the electrophysiological properties of several classes of neurones in the vertebrate retina^3–5. We have combined the method developed previously for examining the neurochemistry of individual retinal cells^1,2 with a single-electrode clamp technique^6,7 to investigate the biophysical properties of isolated horizontal cells from the teleost retina. Our results suggest that the specific membrane capacity of these cells is ∼1 µF cm⁻², and that the specific membrane resistivity ranges from ∼5,000 to 20,000 Ω cm². In isolation, these cells can show regenerative voltage responses which are most probably calcium-dependent.