Dopamine modulates voltage-activated potassium currents in zebrafish retinal on bipolar cells

✍ Scribed by Chuan-Jiang Yu; Lei Li

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 469 KB
• Volume: 82
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.20637

✦ Synopsis

We report a study of the characterization of voltageactivated potassium (K þ ) currents in retinal ON bipolar cells in zebrafish. At single-channels levels, the open probability of the K þ channels increased when the membrane potential was increased. The maximal open proportion was 0.76 6 0.05 under our testing conditions. In whole-cell recordings, the K þ current displayed two exponential components with the activation time constants of 11-22 msec (tau1) and 0.8-4 msec (tau2). Dopamine modulated the K þ current. Dopamine reduced the time constant tau2 when the membrane potential was depolarized to high voltages. A decrease in K þ current was seen when dopamine D 1 receptors were selectively activated by SKF38393 or when the D 1 receptor-coupled G-proteins were activated by GTP-g-S. The activation of adenylate cyclase by forskolin or the increase of intracellular cAMP concentrations by 8-Br-cAMP or Sp-cAMPS also resulted in a decrease in K þ current. Together, the data suggest that dopamine modulates the K þ current via D 1 receptor-coupled Gprotein pathways.