[3H]substance P binding in the intermediolateral cell column and striatum of the rat

[3H]substance P binding was studied in the intermediolateral cell column and striatum in the rat using slide-mounted sections. The intermediolateral cell column had a single high affinity binding component with a dissociation constant, Kd = 1.45 nM and the number of sites, Bmax = 18.1 fmol per mg protein. The striatum had a Kd = 0.77 nM and a Bmax = 23.5 fmol per mg protein. The relative potency of various substance P-like tachykinins in displacing [3H]substance P suggested that both these areas may contain a substance P-P (for physalaemin) receptor subtype. (D-Pro4, D-Trp7,9)substance P(4-11), a substance P antagonist, has a relatively low affinity (micromolar range) in both these areas.