Adrenergic receptors in rat spinal cord.

Radioligand binding assays were used to demonstrate the presence of alpha 1, alpha 2 and beta receptors in rat spinal cord. Specific and saturable binding was exhibited for [3H]-WB 4101 (alpha 1), [3H]-aminoclonidine (alpha 2) and [3H]-dihydroalprenolol (beta). Binding was of high affinity and the total number of binding sites (Bmax) were: alpha 1, 66.5 +/- 1.0 fmol/mg protein; alpha 2, 20.0 +/- 0.6 fmol/mg protein; beta, 10.2 +/- 0.3 fmol/mg protein. The data confirms the existence of adrenergic receptors in spinal cord and provides further evidence of the role of catecholaminergic neurons in regulating spinal cord physiology.