Distribution of potassium conductance in mammalian Müller (glial) cells: a comparative study.

作者：Eric A. Newman · 发表于：PubMed · 年份：1987 · 被引用次数：173 · 研究领域：Retinal Development and Disorders、Neuroscience and Neuropharmacology Research、Connexins and lens biology

The distribution of K+ conductance across the surface of retinal Müller cells was determined in 5 mammalian species--rabbit, guinea pig, mouse, owl monkey, and cat--and in tiger salamander. Potassium conductance was measured by monitoring cell depolarizations evoked by focal ejections of a high-K+ solution onto the surface of freshly dissociated cells. This technique measured the total K+ conductance of a given cell region (regional conductance), i.e., the specific K+ conductance times the total surface area in that region. In mammalian species with avascular retinas (rabbit, guinea pig), the regional K+ conductance within the middle portion of the cell was only a fraction (10.6-28.9%) of the endfoot conductance, while the conductance of the distal (photo-receptor) end of the cell was approximately half (41.2-49.8%) the endfoot conductance. In 2 species with vascularized retinas (mouse and owl monkey), by contrast, the regional K+ conductance within the middle portion of the cell was as large as 125.5-129.8% of the endfoot conductance. In these cells the K+ conductance of the distal end was 68.3-82.9% of the endfoot value. In cat, a third vascularized species, the K+ conductance was highest (187.1% of the endfoot value) at the distal end of the cell. In tiger salamander, which has an avascular retina, the regional K+ conductance of all regions distal to the endfoot was only 2.4-15.7% of the endfoot value. Differences in the distributions of regional K+ conductance observed in...