Figure 4.

The effect of tachykinin receptor antagonists, when perfused with substance P. (a) Pooled data showing for each antagonist; control paired pulse depression using an interstimulus interval of 20 ms (PS2 amplitude expressed as a % of PS1, open bars), the effect of 8 μM substance P (filled bars), the effect of antagonist alone (diagonally hatched bars) and the effect of substance P in the presence of SR140333, MDL29,913 or [Trp⁷, β-Ala⁸]-neurokinin A (4–10) (horizontally hatched bars). The neurokinin-1 receptor antagonist SR140333 (12 μM) significantly reduced the effect of substance P. * denotes P > 0.05, n = 6. The neurokinin-2 receptor antagonist MDl29,913 (12 μM, n = 4) and the NK-3 antagonist [Trp⁷, β-Ala⁸]-neurokinin A (4–10) (5 μM, n = 3), had no significant effecton the action of substance P (b) Example synaptic response recorded from 3 representative slices showing control responses (top row), responses recorded in the presence of substance P (middle row), and responses recorded in the presence of substance P and the antagonist (bottom row). Scale bar represents 1 mV and 10 ms.