OSMOTIC STRENGTH DIFFERENTIATES BETWEEN 2 TYPES OF CALCIUM-TRANSPORT PATHWAYS REGULATING CATECHOLAMINE SECRETION FROM CULTURED BOVINE CHROMAFFIN CELLS

E HELDMAN, M LEVINE, K MORITA, HB POLLARD

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Calcium transport and catecholamine secretion was measured in cultured bovine chromaffin cells. Calcium ions which entered the cells following stimulation with either nicotine or 50 mM KCl (high potassium) triggered catecholamine release, but then inactivated the secretory process. The nicotine and the high potassium-induced calcium transport mechanisms were mechanistically distinct, but functionally dependent on each other. The specific evidence is that whereas the high potassium-induced Ca2+ influx was found to be inhibited by hyperosmotic medium, the nicotine-stimulated calcium influx was unaffected under these conditions. High potassium and nicotine-stimulated catecholamine release were also differently affected by hyperosmotic medium. While potassium-stimulated catecholamine release was profoundly inhibited by hyperosmolarity, nicotine-stimulated release was only moderately inhibited. Sequential treatments of cells with nicotine and high potassium, under isotonic physiological conditions, indicate that there is a functional, biochemical communication between the otherwise mechanistically distinct calcium channels. Calcium ions which were found to inactivate these channels may be the basis for such communication.
    Original languageEnglish
    Pages (from-to)417-425
    Number of pages9
    JournalBiochimica et Biophysica Acta - General Subjects
    Volume1091
    Issue number3
    DOIs
    StatePublished - 19 Feb 1991

    Keywords

    • CALCIUM INFLUX
    • CATECHOLAMINE SECRETION
    • OSMOTIC STRENGTH
    • NICOTINIC RECEPTOR
    • VOLTAGE-DEPENDENT CALCIUM CHANNEL
    • (CHROMAFFIN-CELL)

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