Calcium-dependent prepotentials contribute to spontaneous activity in rat tuberomammillary neurons.
AUTOR(ES)
Stevens, D R
RESUMO
1. Intracellular recordings from histaminergic neurons of the tuberomammillary (TM) nucleus reveal subthreshold depolarizing potentials (DPs) which persist in the presence of tetrodotoxin. 2. Block of hyperpolarization-activated current by 1-4 mM Cs+ failed to reduce spontaneous activity or DPs. 3. In the presence of tetrodotoxin DPs are voltage dependent and are depressed by Cd2+ and Co2+. 4. Ba2+ (100 microM) treatment enhances DP amplitude and converts low-amplitude potentials to tetrodotoxin-insensitive action potentials. 5. In the presence of TTX, DPs are reduced by Ni2+. Spontaneous action potentials are also reduced by Ni2+ (100-300 microM). A low-threshold Ca2+ current is present which is sensitive to Ni2+. These results indicate the presence of calcium currents, perhaps of the low-threshold type, which contribute to activation of action potentials in TM neurons.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1159022Documentos Relacionados
- Calcium-dependent chloride current induced by axotomy in rat sympathetic neurons.
- Heat transduction in rat sensory neurons by calcium-dependent activation of a cation channel
- Calcium-dependent chloride secretion in rat colon epithelium.
- Roles of arachidonic acid, lipoxygenases and phosphatases in calcium-dependent modulation of M-current in bullfrog sympathetic neurons.
- The calcium-dependent potassium conductance in rat sympathetic neurones.
