Serotonin and forskolin increase an inwardly rectifying potassium conductance in cultured identified Aplysia neurons.
1. The effect of serotonin (5-HT) and forskolin on an inwardly rectifying K+ conductance (IKR) was studied using voltage-clamp techniques in several identified Aplysia neurons isolated and maintained in primary cell culture. 2. Inward rectification was observed in the current-voltage relationship of the identified neurons R15, R2, B1, and B2 and was predominately due to IKR, as demonstrated by the dependence of inward rectification on the extracellular K+ concentration, instantaneous kinetics of the membrane current response to hyperpolarizing voltage clamp pulses, and voltage-dependent Ba2+ block of the inwardly rectifying current. 3. 5-HT increased IKR conductance between 100 and 400% in the identified neuron R15 in culture and increased IKR conductance approximately 50% in the identified neurons B1, B2, and R2 in culture. The adenylate cyclase activator, forskolin, plus a phosphodiesterase inhibitor, Ro 20-1724, also increased IKR conductance in these neurons. 4. 5-HT and forskolin modulated other ion conductances as well in all of these cultured neurons.
Lotshaw
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DP
Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254.
Levitan
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IB
D000818:Animals; D001048:Aplysia; D001464:Barium / Q000494:pharmacology; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology*; D004553:Electric Conductivity; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology*; D012701:Serotonin / Q000494:pharmacology*
D005576:Colforsin; D001464:Barium; D012701:Serotonin; D011188:Potassium