. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Control. 0 10 20 30 40 50 60 70 80 90 100 110 120 time (sec) 200 pM quinidine Control 20 25 30 35 40 45 time (sec) Figure 1. Effect of quinidine on the level of intracellular calcium in a horizontal cell isolated from the skate retina. Bottom traces: Currents elicited from a skale horizontal cell in response to a 24-s voltage step to +30 ml 'from a ho/ding potential of- 70 in I' Measurements were made initially with the cell bathed in skale Ringer (control), and again after nun superfusion with 200 pM quinidine. The Ring
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Control. 0 10 20 30 40 50 60 70 80 90 100 110 120 time (sec) 200 pM quinidine Control 20 25 30 35 40 45 time (sec) Figure 1. Effect of quinidine on the level of intracellular calcium in a horizontal cell isolated from the skate retina. Bottom traces: Currents elicited from a skale horizontal cell in response to a 24-s voltage step to +30 ml 'from a ho/ding potential of- 70 in I' Measurements were made initially with the cell bathed in skale Ringer (control), and again after nun superfusion with 200 pM quinidine. The Ringer solution was supplemented with 100 nM nifedipine to block voltage-gated calcium conductances and a cocktail of compounds to reduce contributions from other voltage-gated conductances (5). Top traces: The internal calcium concentration from the same cell measured simultaneously. No increase in calcium was noted with the cell bathed in Ringer, while a large increase in calcium was delected when the quinine-induced current was activated. Two additional cells showed even greater increases in internal calcium (~~ 2 nAf) in the presence of quinidine; these cells also displayed small (< 200 nM) but significant rises in calcium when depolarized in control Ringer. 3. Saez, J. C., J. A. Conner, D. C. Spray, and M. V. L. Bennett. 1989. 86: 2708-2712. 4. Christ, G. J., A. P. Moreno, A. Melman, and D. C. Spray. 1992. Am. J Physiol. 263: C373-C383. 5. Malchow, R. P., II. Qian, and H. Ripps. 1993. J. Neurosci. Res 35: 237-245. Reference: Biol. Bull 187: 263-265. (October, 1994) The GABAA Receptors of Miiller (Glial) Cells in Skate Retina Haohua Qian (Harvard University). Robert Paul Malchow, Richard L. Chappell, and Harris Ripps The circuitry of the vertebrate retina is formed by intercon- necting networks of neural pathways, and subtle alterations in synaptic transmission can exert profound effects on the activity of a given pathway. There is growing evidence that glial cells pa
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