[Dopamine receptors of the smooth muscles]

It is shown that the interuption of sympathetic nerves in the smooth muscles of the deferent duct or ejejunum of rats achieved by a 4-day keeping of the duct in cold or by the reserpine treatment of the animals does not produce any essential effect on the dopamine action. The contraction of smooth muscles in the isolated deferent duct, mesenteric and renal vessels of rats is effectively eliminated by alpha-andrenolytics (dihydroergotoxin, phentolamine), while the inhibitory effects of dopamine (lowering of vasotonicity of the rats' jejunum tone) are suppressed with propranolol. Galoperidol and methylergometrin display in experiments with smooth muscle organs but a low degree of antagonism to dopamine. The activity of phentolamine as an antagonist of norepinephrine and dopamine in the deferent duct is identical.