title: Effects of Cl(-) substitution on electrophysiological properties, Ca(2+) influx and prolactin secretion of rat lactotropes in vitro.
abstract: In this study, we compared the effects of different chloride (Cl(-)) substitutes - methane sulfonate (CH(3)SO(-)(3)), bromide (Br(-)), nitrate (NO(-)(3)), thiocyanate (SCN(-)) and perchlorate (ClO(-)(4)) - on the secretory activity and calcium current activation of rat lactotropes in primary culture. We observed that CH(3)SO(-)(3) decreased basal prolactin (PRL) secretion. Br(-) had no effect, whereas the more lyotropic anions, such as NO(-3), SCN(-) and C1O(-4), increased basal PRL secretion. The latter three substitutes induced a significant shift in the voltage dependence of T-type calcium channel activation towards hyperpolarized values. However, this shift alone cannot explain the increase in secretion. Anion permeability studies also demonstrated that the organic anion CH(3)SO(-3) was less permeant than Cl(-), whereas monovalent inorganic anions were more permeant, with the following anion permeability sequence: SCN(-) > ClO(-4) > NO(-3) > Br(-). In conclusion, deprivation of Cl(-) ions has converse consequences on basal and induced secretion; permeating anions result in a transient increase in intracellular Ca(2+) ions. This process involves voltage-dependent Ca(2+) channels. We propose that an alteration in intracellular anion concentrations may influence the activation of internal effectors such as G proteins or channel proteins and, therefore, interfere with exocytosis. These effects are correlated with an external action of lyotropic anions, particularly NO(-3), ClO(-4) and SCN(-), on the gating properties of T-type calcium channels, probably through changes in cell surface charges. The results demonstrate the modulatory effect of anions on the secretory activity of rat lactotropes and underline the specific role played by chloride in stimulus-secretion coupling.
authors.affiliation: Departamento de Ciencias Fisiologicas, Facultad de Salud, Universidad del Valle, Cali, Colombia.
authors.forename: L
authors.initials: L
authors.lastname: Garcia
authors.forename: B
authors.initials: B
authors.lastname: Couderc
authors.forename: M F
authors.initials: MF
authors.lastname: Odessa
authors.forename: L
authors.initials: L
authors.lastname: Dufy-Barbe
authors.forename: P
authors.initials: P
authors.lastname: Sartor
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001965:Bromides / Q000494:pharmacology; D002118:Calcium / Q000493:pharmacokinetics*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D020747:Calcium Channels, T-Type / Q000502:physiology; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D008698:Mesylates / Q000494:pharmacology*; D009566:Nitrates / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010472:Perchlorates / Q000494:pharmacology; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017670:Sodium Compounds / Q000494:pharmacology; D013861:Thiocyanates / Q000494:pharmacology
chemical_list: D001965:Bromides; D002120:Calcium Channel Agonists; D020747:Calcium Channels, T-Type; D002712:Chlorides; D008698:Mesylates; D009566:Nitrates; D010472:Perchlorates; D017670:Sodium Compounds; D013861:Thiocyanates; C045880:methanesulfonic acid; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D011388:Prolactin; C031068:sodium perchlorate; C031760:thiocyanate; D002118:Calcium