Protein kinase C isoform specificity of cholinergic potentiation of glucose-induced pulsatile 5-HT/ insulin release from mouse pancreatic islets

• INÊS E BALDEIRAS ^[1] ; ROSA M SANTOS ^[1] ; LUÍS M ROSÁRIO ^[1]
  1. [1] Universidade de Coimbra

     Universidade de Coimbra

     Coimbra (Sé Nova), Portugal

     
• Localización: Biological Research, ISSN-e 0717-6287, ISSN 0716-9760, Vol. 39, Nº. 3, 2006, págs. 531-539
• Idioma: inglés
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• Resumen

  • Thymeleatoxin (TMX), an activator of Ca2+-sensitive protein kinase C (cPKC) isoforms, was used to assess the PKC isoform specificity of cholinergic potentiation of glucose (11 mM)-induced pulsatile 5-HT/insulin release (PIR) from single mouse pancreatic islets. TMX (100 nM) and carbachol (Cch, 50 mM) enhanced PIR ~ 3-fold while reducing the underlying [Ca2+]i oscillations (duration and amplitude) by ~ 40-50%. Both effects were ablated by the specific PKC inhibitor bisindolylmaleimide and chronic TMX pretreatment. Cch also evoked an initial transient [Ca2+]i rise and surge of 5-HT release, which remained unaffected by chronic TMX pretreatment. It is concluded that the immediate cholinergic responses are insensitive to cPKC. In contrast, specific activation of a cPKC isoform mediates sustained cholinergic potentiation of glucose-induced insulin secretion.