Ryanodine-sensitive calcium stores involved in neurotransmitter release from sympathetic nerve terminals of the guinea-pig.
AUTOR(ES)
Smith, A B
RESUMO
1. Intracellular and focal extracellular recording techniques were used to study neurotransmitter release mechanisms in postganglionic sympathetic nerve terminals in the guinea-pig isolated vas deferens. 2. High concentrations of the selective N-type calcium channel blocker omega-conotoxin GVIA abolished the release of the neurotransmitter ATP evoked by trains of low-frequency stimuli. However, in the presence of high concentrations of the blocker, a 'residual release' persisted at higher frequencies. 3. Residual release was dependent on calcium entry through a pharmacologically distinct voltage-dependent calcium channel. 4. Residual release was inhibited by ryanodine in a use- and time-dependent manner and this inhibitory effect was potentiated by caffeine. The inhibitory effect of ryanodine on residual release was reversed by 4-aminopyridine. 5. These findings indicate that calcium-induced calcium released from intraneuronal stores plays an important role in action potential-evoked neurotransmitter release mechanisms in postganglionic sympathetic nerve terminals.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1160962Documentos Relacionados
- Release and sequestration of calcium by ryanodine-sensitive stores in rat hippocampal neurones.
- Multiple calcium channels control neurotransmitter release from rat postganglionic sympathetic nerve terminals.
- A model of calcium dynamics in cardiac myocytes based on the kinetics of ryanodine-sensitive calcium channels.
- Effects of sympathetic nerve stimulation on the sino-atrial node of the guinea-pig.
- Glucose-sensitive afferent nerve fibres in the hepatic branch of the vagus nerve in the guinea-pig.
