Serotonin modulates the voltage dependence of delayed rectifier and Shaker potassium channels in Drosophila photoreceptors.
We describe the in situ modulation of potassium channels in a semi-intact preparation of the Drosophila retina. In whole-cell recordings of photoreceptors, rapidly inactivating Shaker channels are characterized by a conspicuously negative voltage operating range; together with a delayed rectifier, these channels are specifically modulated by the putative efferent neurotransmitter serotonin. Contrary to most potassium channel modulations, serotonin induced a reversible positive shift in the voltage operating range, of +30 mV for the Shaker channels and +10-14 mV for the delayed rectifier. The maximal current amplitudes were unaffected. Modulation was not affected by the subunit-specific Shaker mutations ShE62 and T(1;Y)W32 or a null mutation of the putative modulatory subunit eag. The modulation of both channels was mimicked by intracellularly applied GTP gamma S.
Hevers
W
W
University of Cambridge, Department of Zoology, England.
Hardie
R C
RC
D000818:Animals; D004331:Drosophila melanogaster / Q000502:physiology*; D004553:Electric Conductivity; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D012160:Retina / Q000737:chemistry; D012701:Serotonin / Q000494:pharmacology*
D015221:Potassium Channels; D012701:Serotonin; D016244:Guanosine 5'-O-(3-Thiotriphosphate)