Multiple actions of a molluscan cardioexcitatory neuropeptide and related peptides on identified Helix neurones.
AUTOR(ES)
Cottrell, G A
RESUMO
The effects of the molluscan neuropeptide Phe-Met-Arg-Phe-NH2 (FMRF amide) and related peptides (Price & Greenberg, 1977) were tested on Helix aspersa neurones. Ionophoretic application of FMRFamide depolarized and excited some neurones, but hyperpolarized and inhibited others. In some neurones the sign of the response was dependent on the membrane potential. Two responses resulted from an increase in membrane conductance, a depolarizing response mediated mainly by an increase in Na+ ion permeability, and a hyperpolarizing response mediated by an increase in K+ ion permeability. In the C1 neurone a voltage-dependent response was observed, which only occurred when the neurone was depolarized from its resting level. This response was recorded as an inward current during voltage clamp and resulted from a decrease in K current(s), possibly Ca-activated K current. More than one response may occur in a single neurone. In the C1 neurone, the K-mediated hyperpolarization occurred as well as the voltage-dependent response, while the depolarization seen in the F2 neurone was a combination of an increase in Na conductance and an increase in K conductance.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1193166Documentos Relacionados
- Multiple receptor sites for a molluscan peptide (FMRFamide) and related peptides of Helix.
- Copper activates a unique inward current in molluscan neurones.
- Actions of substance P on rat spinal dorsal horn neurones.
- Evidence for parallel actions of a molluscan neuropeptide and serotonin in mediating arousal in Aplysia.
- On the nature of histamine-mediated slow hyperpolarizing synaptic potentials in identified molluscan neurones