Presynaptic inhibition in Aplysia involves a decrease in the Ca2+ current of the presynaptic neuron.
AUTOR(ES)
Shapiro, E
RESUMO
By voltage clamping presynaptic cell L10 and using pharmacologic separation techniques, we have analyzed the specific ionic currents in the presynaptic cell that correlate with presynaptic inhibition while assaying transmitter release with intracellular recordings from postsynaptic cells. We have found that presynaptic inhibition can be elicited in conditions in which the Na+ and the various K+ channels are pharmacologically blocked and depolarizing current pulses produce only an inward Ca2+ current. Both inward currents and tail currents at and above the K+ reversal potential were always less inward during presynaptic inhibition. The changes in conductance associated with presynaptic inhibition were voltage sensitive and paralleled the voltage sensitivity of the Ca2+ channel. We therefore conclude that presynaptic inhibition is caused by a direct transmitter-mediated decreased of presynaptic Ca2+-channel conductance.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=348450Documentos Relacionados
- Post-tetanic potentiation at an identified synapse in Aplysia is correlated with a Ca2+-activated K+ current in the presynaptic neuron: evidence for Ca2+ accumulation.
- Enhancement by muscarinic agonists of a high voltage-activated Ca2+ current via phosphorylation in a snail neuron.
- Presynaptic modulation of voltage-dependent Ca2+ current: Mechanism for behavioral sensitization in Aplysia californica
- Transient low-threshold Ca2+ current triggers burst firing through an afterdepolarizing potential in an adult mammalian neuron.
- Presynaptic membrane potential affects transmitter release in an identified neuron in Aplysia by modulating the Ca2+ and K+ currents