[Desensitization of alpha-adrenoreceptors of the small intestine of the rat].

A study performed on the isolated section of the rat small intestine has shown that at a slow increase in the concentration of the specific alpha-adrenomimetic phenylephrine in the incubation medium 1.0 X 10(-8) M/sec) adrenoreceptors pass into a state of desensitization without excitation, and no reaction takes place. At 2.5 X 10(-8)-10 X 10(-8) M/sec the reaction develops depending on the rate of phenylephrine introduction and is stabilized at 5.5-5.8 X 10(-6) M. Apparently, under these conditions an equilibrium is set up between activation and desensitization of adrenoreceptors. The role of desensitization of alpha-adrenoreceptors in the regulation of adrenergic reaction is discussed.