[Ca2+]i oscillations in single rat glioma cells induced by thrombin through activation of cell surface receptors

Thrombin at nanomolar concentrations induces rapid changes in the second messenger Ca2+ in a glial astrocyte-type cell line. Continuous application of the protease thrombin causes regular [Ca2+]i oscillations (amplitude 109 nM, spike length 48 s) which are suppressed by hirudin. Reduction of [Ca2+]ex (from 1.8 mM to 50 microM) reversibly abolishes the oscillations indicating the contribution of Ca2+ influx to generation of the oscillations. Thrombin receptor-activating peptide (TRAP, 1-10 microM) causes similar Ca2+ oscillations which depend, like the oscillations induced by thrombin, on the continuous presence of agonist. Thus, we can deduce that cell surface receptors are responsible for the effect of thrombin on glioma cells.