Wh. Baldridge et al., Taurine blocks spontaneous cone contraction but not horizontal cell dark suppression in isolated goldfish retina, J NEUROCHEM, 74(6), 2000, pp. 2614-2621
The objective of this study was to investigate the effects of taurine on co
ne retinomotor movements and the responses of cone-driven horizontal cells
in dark-adapted teleost retina. In isolated goldfish retina preparations ma
intained in the dark, cones spontaneously contracted, and the responses of
horizontal cells were suppressed. Addition of 5 mM taurine to the physiolog
ical solution blocked the spontaneous contraction of cones in the dark but
did not block the dark-suppression of horizontal cell responses. These resu
lts indicate that the mechanism that leads to horizontal cell dark suppress
ion is not sensitive to taurine. Although both cone retinomotor position an
d horizontal cell responsiveness are known to be modulated by dopamine, the
present results do not support the hypothesis that taurine inhibits dopami
ne release in the dark because only spontaneous cone contraction was affect
ed by taurine. These results also indicate that spontaneous cone contractio
n in the dark is not the cause of horizontal cell dark suppression because,
in the presence of taurine, canes were elongated yet horizontal cell respo
nses were still suppressed. Consequently, these results make it clear that
horizontal cell dark suppression is not an artifact produced by incubating
isolated teleost retina preparations in taurine-free physiological solution
.