Journal of Neurophysiology, Vol 58, Issue 5 909-921, Copyright © 1987 by APS
Serotonin and forskolin increase an inwardly rectifying potassium conductance in cultured identified Aplysia neurons
D. P. Lotshaw and I. B. Levitan
Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254.
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.
