title: Electrical activity-triggered glucagon-like peptide-1 secretion from primary murine L-cells.
abstract: Glucagon like peptide 1 (GLP-1) based therapies are now widely used for the treatment of type 2 diabetes. Developing our understanding of intestinal GLP-1 release may facilitate the development of new therapeutics aimed at targeting the GLP-1 producing L-cells. This study was undertaken to characterise the electrical activity of primary L-cells and the importance of voltage gated sodium and calcium channels for GLP-1 secretion. Primary murine L-cells were identified and purified using transgenic mice expressing a fluorescent protein driven by the proglucagon promoter. Fluorescent L-cells were identified within primary colonic cultures for patch clamp recordings. GLP-1 secretion was measured from primary colonic cultures. L-cells purified by flow cytometry were used to measure gene expression by microarray and quantitative RT-PCR. Electrical activity in L-cells was due to large voltage gated sodium currents, inhibition of which by tetrodotoxin reduced both basal and glutamine-stimulated GLP-1 secretion. Voltage gated calcium channels were predominantly of the L-type, Q-type and T-type, by expression analysis, consistent with the finding that GLP-1 release was blocked both by nifedipine and ω-conotoxin MVIIC. We observed large voltage-dependent potassium currents, but only a small chromanol sensitive current that might be attributable to KCNQ1. GLP-1 release from primary L-cells is linked to electrical activity and activation of L-type and Q-type calcium currents. The concept of an electrically excitable L-cell provides a basis for understanding how GLP-1 release may be modulated by nutrient, hormonal and pharmaceutical stimuli.
authors.affiliation: Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Box 139, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: G J
authors.initials: GJ
authors.lastname: Rogers
authors.forename: G
authors.initials: G
authors.lastname: Tolhurst
authors.forename: A
authors.initials: A
authors.lastname: Ramzan
authors.forename: A M
authors.initials: AM
authors.lastname: Habib
authors.forename: H E
authors.initials: HE
authors.lastname: Parker
authors.forename: F M
authors.initials: FM
authors.lastname: Gribble
authors.forename: F
authors.initials: F
authors.lastname: Reimann
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004558:Electric Stimulation; D004594:Electrophysiology; D019858:Enteroendocrine Cells / Q000187:drug effects / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009543:Nifedipine / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D052216:Glucagon-Like Peptide 1; D009543:Nifedipine; D002118:Calcium