Neuroligand-evoked calcium-dependent release of excitatory amino acids from Schwann cells

Abstract

Bradykinin caused a receptor-mediated increase in release of the excitatory amino acids (EAAs) glutamate and aspartate from Schwann cell cultures obtained from dorsal root ganglia (DRG) together with an increase in the cytoplasmic level of free calcium. Perturbations which inhibited brady-kinin-induced calcium mobilization prevented the release of EAAs from glia. The addition of ionomycin caused a calcium-dependent release of EAAs. Therefore, bradykinin causes calcium dependent-release of EAAs from DRG Schwann cells. Bradykinin did not cause cell swelling and p-chloromercuriphenylsulfonic acid, an inhibitor of the electrogenic glutamate transporter, did not reduce bradykinin-induced EAA release. Therefore, bradykinin stimulates EAA release from Schwann cells through a mechanism that is neither the previously described volume regulated release mechanism nor due to the reversal of the glutamate transporter.