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- Title
Galanin suppresses calcium conductance and activates inwardly rectifying potassium channels in myenteric neurones from guinea-pig small intestine.
- Authors
Ren, J.; Hu, H. Z.; Starodub, A. L. M.; Wood, J. D.
- Abstract
Whole-cell patch-clamp recording methods were used to investigate the ionic mechanisms underlying the hyperpolarizing action of galanin in enteric neurones. Galanin suppressed calcium current (I[subCa]) and activated inwardly rectifying potassium current (I[subK,ir]) in AH-type myenteric neurones of guinea-pig small intestine. Both suppression of I[subCa] and activation of I[subK,ir] were concentration-dependent, with an EC[sub50] of 1.4 nmol L[sup-1] and 55 nmoI L[sub-1], respectively. Pretreatment with pertussis toxin eliminated both actions of galanin, suggesting that both galanininduced inhibition of I[subCa] and galanin-induced activation of I[subK,ir] involved activation of G[subi]/G[subo] proteins. Both suppression of I[Ca] and activation of I[subK,ir] by galanin were mimicked by the N-terminal fragment of galanin, galanin-(l-16) suggesting that the first 16 amino acids of the peptide were sufficient for both actions. The galanin receptor antagonist galantide suppressed the galanin-induced activation of I[K,ir] with an EC[sub50] of 16 nmol L[sup-1]. However, galantide alone suppressed I[subCa]. The results suggest two mechanisms of action for galanin: one is opening of inwardly rectifying potassium channels and the second is blockade of voltage-activated calcium channels.
- Subjects
GALANIN; NEURONS; GUINEA pigs; SMALL intestine
- Publication
Neurogastroenterology & Motility, 2001, Vol 13, Issue 3, p247
- ISSN
1350-1925
- Publication type
Article
- DOI
10.1046/j.1365-2982.2001.00264.x