Dopamine-induced inhibition of synaptic transmission in lumbar paravertebral ganglia of the dog.

Abstract

Dopamine, injected into the lumbar aorta in doses which produce a neurogenic vasodilatation in the isolated perfused hindleg of the dog (0.5–64×10−8 moles), provokes a reversible inhibitory of the synaptic transmission in the paravertebral lumbar ganglia. This inhibitory effect is mimicked by epinine (1–64×10−8 moles) and apomorphine (0.6–38.4×10−8 moles) and is preferentially blocked by haloperidol (0.26×10−6 moles), pimozide (2.2×10−6 moles) and aceperone (2.5×10−6 moles). (-)-Noradrenaline (0.6–19.2×10−8 moles) is equipotent with dopamine in inhibiting ganglionic transmission; this noradrenaline inhibitory effect is preferentially blocked by phentolamine (8×10−6 moles).