Potassium conductance in Müller cells of fish

• Published in: Glia
• Main Author: Newman, Eric A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1988
• Subjects: spiny dogfish; Squalus acanthias
• Online Access: http://dx.doi.org/10.1002/glia.440010406; http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fglia.440010406; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fglia.440010406; https://onlinelibrary.wiley.com/doi/pdf/10.1002/glia.440010406

Abstract The distribution of potassium conductance across the surface of retinal glial (Müller) cells was determined in three species of fishes: two teleosts, the goldfish ( Carassius auratus ) and the alewife ( Alosa pseudoharengus ), and an elasmobranch, the spiny dogfish ( Squalus acanthias ). Potassium conductance was measured by monitoring cell depolarizations evoked by focal ejections of a 15 mEq/L K + solution onto the surface of freshly dissociated cells. The K + conductance distributions observed in these three species resembled those found previously in other animals with avascular retinas. In both alewife and dogfish, K + conductance was highest in the endfoot; K + conductance in the distal half of these cells ranged from 7.0 to 22.9% of the endfoot conductance. In goldfish, in contrast, K + conductance was highest in the proximal region of the proximal process (114% of the endfoot conductance). As in the two other species, however, K + conductance in goldfish was low in the distal half of the cell (7.6 to 40.1% of endfoot conductance). Mean input resistance values of isolated cells were as follows: goldfish, 12.5 MΩ; alewife, 26.4 MΩ; dogfish, 38.0 MΩ. The high resistance of dogfish Müller cells lacking their endfeet (749 MΩ) indicates that 95% of the cell membrane conductance is located in or near the endfoot in this species.