title: Intestinal and peritoneal mast cells differ in kinetics of quantal release.
abstract: 5-hydroxytriptamine (5-HT, serotonin) storage and release in mast cell (MC) secretory granules (SG) are dependent on serglycin proteoglycans (PG). This notion is based on the studies of MC of the connective tissue subtype that predominantly contain PG of the heparin type, whereas intestinal mucosal MC, which contain predominantly chondroitin sulfate, have been poorly explored. In the present study, we addressed the possibility that PG contents may differently affect the storage and release of preformed mediators in these two MC subclasses and explain in part their different functional properties. Rat peritoneal (PMC) and intestinal mast cells (IMC) were isolated and purified using a percoll gradient, and the efflux of 5-HT from each SG was measured by amperometric detection. IMC exhibited a ∼34% reduction in the release of 5-HT compared with PMC because of a lower number of exocytotic events, rather than a lower secretion per single exocytotic event. Amperometric spikes from IMC exhibited a slower decay phase and increased half-width but a similar ascending phase and foot parameters, indicating that the fusion pore kinetics are comparable in both MC subclasses. We conclude that both PG subtypes are equally efficient systems, directly involved in serotonin accumulation, and play a crucial role in regulating the kinetics of exocytosis from SG, providing specific secretory properties for the two cellular subtypes.
authors.affiliation: Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain. Electronic address: sanbalgom@alum.us.es.
authors.forename: Santiago
authors.initials: S
authors.lastname: Balseiro-Gomez
authors.affiliation: Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain. Electronic address: pponce@us.es.
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Ramirez-Ponce
authors.affiliation: Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain. Electronic address: jorgealo@us.es.
authors.forename: Jorge
authors.initials: J
authors.lastname: Acosta
authors.affiliation: Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain. Electronic address: eales@us.es.
authors.forename: Eva
authors.initials: E
authors.lastname: Ales
authors.affiliation: Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain. Electronic address: jaflores@us.es.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Flores
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005089:Exocytosis / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology*; D007700:Kinetics; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D009928:Organ Specificity / Q000502:physiology; D010537:Peritoneum / Q000166:cytology* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin
keywords: Amperometry; Exocytosis; Mast cells; Proteoglycans and serotonin