[ ³ H]-5-Carboxamidotryptamine (5-CT) binding to 5-HT _1D sites in bovine substantia nigra is rapid, reversible and saturable, displaying high affinity (K _d = 0.38 nM) and low non-specific binding.
In bovine substantia nigra, [ ³ H]-5-Carboxamidotryptamine (5-CT) labelled an equivalent number of binding sites to [ ³ H]-5-Carboxamidotryptamine (403 and 362 fmol/mg protein, respectively) and binding is sensitive to guanine nucleotides.

Topical 5-Carboxamidotryptamine (0.01-1000 μM) to the exposed dura mater encephala produced decreases in diastolic blood pressure, variable changes in meningeal blood flow and increases in conductance (i.e. dilatation) in the middle meningeal artery of anesthetized Wistar rats (serotonin depletion and treated with 20 mg/kg corticosterone).