title: A secondary metabolite, 4,5-dibromopyrrole-2-carboxylic acid, from marine sponges of the genus Agelas alters cellular calcium signals.
abstract: A secondary metabolite from sponges of the genus Agelas, 4,5-dibromopyrrole-2-carboxylic acid, which is well known as feeding deterrent, was investigated for effects on the cellular calcium homeostasis in PC12 cells. 4,5-Dibromopyrrole-2-carboxylic acid did not change intracellular calcium levels if applied alone without cell depolarization. During depolarization of the cellular membrane using high potassium solution, a dose dependent reduction of intracellular calcium elevation was revealed utilizing Fura II as calcium indicator. Significant reduction was seen at concentrations higher than 30μM in a series of experiments, but in single experiments a concentration of 300nM was still reversible effective. In the same concentration range, the onset of depolarization induced calcium elevations was significantly delayed by 4,5-dibromopyrrole-2-carboxylic acid. Dose dependent reduction and delay of depolarization evoked calcium elevations are probably due to a reduction of calcium entry via voltage operated calcium channels. One cellular mode of action of the feeding deterrent potential of 4,5-dibromopyrrole-2-carboxylic acid to fishes may be an interaction with the cellular calcium homeostasis of exposed cells.
authors.affiliation: Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Biologische Anstalt Helgoland, Kurpromenade, D-27498 Helgoland, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Bickmeyer
authors.forename: Michael
authors.initials: M
authors.lastname: Assmann
authors.forename: Matthias
authors.initials: M
authors.lastname: Köck
authors.forename: Christian
authors.initials: C
authors.lastname: Schütt