[The alpha-adrenergic sensitivity of smooth muscle following sympathectomy]

The effect of sympathetic nerve stimulation on postsynaptic alpha-adrenoceptors of cat's smooth muscle nictitating membrane was studied. L-noradrenaline, adrenaline, phenylephrine and clonidine caused a concentration-dependent contraction. In denervated tissue, the concentration-response curve for clonidine mainly shifted to the left in comparison with the control; in contrast to the innervated smooth muscle, there were no reliable differences between the constant dissociation Ka and KB for alpha 1- and alpha 2-selective and nonselective adrenomimetics and adrenoblockaders. The data obtained suggest alteration of pharmacological characteristics of smooth muscle alpha-adrenoceptors after interruption of the sympathetic nerve.