Effects of tachykinins on [3H]taurine release from human astrocytoma cells (U-373 MG).

Substance P (SP) stimulated [3H]taurine release from human astrocytoma cells (U-373 MG). This effect was concentration dependent and the EC50 was 0.3 nM. This stimulatory effect of SP can be inhibited by spantide, a SP receptor antagonist. The rank order of potencies of related tachykinins and their analogues in stimulating the release of [3H]taurine was SP much greater than neurokinin A much greater than neurokinin B and [Glp6,L-Pro9]SP (6-11) much greater than [Glp6, D-Pro9]SP (6-11) which conformed to that reported for the tachykinin NK-1 receptor. In addition to SP, isoproterenol, a beta-adrenergic agonist, can also increase the release of [3H]taurine from these cells and the effects of SP and isoproterenol were additive.