Potassium current in Drosophila neurons is increased by either dunce mutation or cyclic AMP.
In the Drosophila mutant dunce, short-term memory is deficient and intracellular cyclic adenosine monophosphate (cAMP) concentration is elevated. We examined the effect of increased cAMP concentration on the potassium current. The conventional whole-cell technique was applied to cultured "giant" Drosophila neurons derived from cell-division arrested embryonic neuroblasts. Potassium membrane currents were measured from: 1) control wild-type neurons, 2) wild-type neurons with dibutyryl cAMP and theophylline in the culture media for 2 days (db-cAMP-treated), and 3) dunce neurons. Delayed-rectifier potassium current was greater in both dunce neurons and db-cAMP-treated wild-type neurons than in control wild-type neurons. This result indicates that the neuronal potassium current is increased by the long-term increase of cAMP. Conceivably, altered neuronal excitability in the dunce mutant could disrupt the processing of neural signals necessary for learning and memory.
Alshuaib
W B
WB
Physiology Department, Faculty of Medicine, Kuwait University, Safat, Kuwait. Waleed@hsc.Kuniv.edu.Kw
Mathew
M V
MV
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics* / Q000502:physiology*; D004553:Electric Conductivity; D008570:Memory, Short-Term / Q000502:physiology; D009154:Mutation / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000502:physiology*; D013806:Theophylline / Q000494:pharmacology
D003994:Bucladesine; D013806:Theophylline; D000242:Cyclic AMP; D011188:Potassium