Biochemical evidence for pharmacological similarities between alpha-adrenoreceptors and voltage-dependent Na+ and Ca++ channels

The α-adrenergic antagonists yohimbine, prazozin and phentolamine, but not the α-adrenergic agonists, block voltage-dependent Na⁺ channels of rat brain synaptosomes. The lipid-soluble neurotoxins (veratridine, aconitine, grayanotoxins and ceveratrum alkaloids), which cause a permanent activation of the Na⁺ channels by acting at the same receptor site as yohimbine, compete with ³H]yohimbine for its binding to rat brain α₂-adrenoreceptors. The calcium channel inhibitors verapamil and D₆₀₀ also block the Na⁺ channel and recognize α₂-adrenoreceptors.