title: Effect of quinine on the release of catecholamines from bovine cultured chromaffin cells.
abstract: 1. The effects of quinine on catecholamine release from cultured bovine chromaffin cells were studied. 2. Quinine (25-400 microM) produced a dose-related inhibition of catecholamine release in response to depolarizing concentrations (12.5-50 mM) of K+. 3. The inhibition of the secretory response to high K+ produced by quinine decreased with the increase in the extracellular concentration of Ca2+. 4. Stimulation of cultured chromaffin cells with 50 mM K+ produced a significant increase in Ca2+ influx. In the presence of 100 microM quinine a 54% inhibition of the K(+)-induced Ca2+ influx was observed. 5. Quinine treatment of chromaffin cell cultures produced a small but significant decrease in membrane resting potential and a less pronounced depolarization in response to 50 mM K+. 6. The results suggest that the inhibition of the K(+)-evoked release of catecholamines produced by quinine is at least partly due to a decrease in Ca2+ influx. Ca2+ influx is lower because quinine reduces the sensitivity of the membrane potential to changes in extracellular K+ but direct effects of quinine on Ca2+ channels cannot be excluded.
authors.affiliation: Department of Pharmacology, Faculty of Health Sciences, University of Ottawa, Ontario, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Tang
authors.forename: M L
authors.initials: ML
authors.lastname: Novas
authors.forename: M I
authors.initials: MI
authors.lastname: Glavinovic
authors.forename: J M
authors.initials: JM
authors.lastname: Trifaró
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002132:Calcium Radioisotopes; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D002838:Chromaffin System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004594:Electrophysiology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000494:pharmacology; D011803:Quinine / Q000494:pharmacology*
chemical_list: D015220:Calcium Channels; D002132:Calcium Radioisotopes; D002395:Catecholamines; D011803:Quinine; D011188:Potassium; D002118:Calcium