Studies on Quinine and Quinidine V. Do They Have a Specific Action on Autonomic Nerve Ends?

Abstract

In an earlier paper in this series 1 it was shown that epinephrine loses part or all of its pressor activity in dogs following injections of quinine or quinidine because of a partial or complete paralysis of the peripheral vasomotor mechanism. This was localized as being on the endings because pituitary solution was still effective in raising the blood pressure. The work has been extended to cats, and it has been found that there is not only a loss of pressor activity but also in some cases a very clear cut vasomotor reversal. Figure 1 illustrates such a case. Here approximately 3 mg. of quinidine per kilo have completely reversed the action of epinephrine. In other similar experiments this same result has been obtained not only from the injection of epinephrine, but also from stimulation of the splanchnics. These findings in cats and dogs suggest a similarity in action between quinine (or quinidine) and the ergot alkaloids. When the reaction of the rabbit uterus to epinephrine before and after quinine or quinidine was examined, there was again noted this reversal. This phenomenon has also been noted by Stake 2 and Langecker. 3 The isolated uterus of the virgin cat which relaxes to epinephrine, gave a greater degree of relaxation after administration of quinine. In 2 experiments the stimulant action of epinephrine for the retractor penis of the dog has been reversed. Because of these positive findings the experiments have been further extended to determine whether quinine and quinidine could be said to act specifically on the motor divisions of the sympathetics. The experiments have been uniformly negative. It has not been possible to show any antagonism for the action of epinephrine or the cervical sympathetic on the dilator iridis or the orbital smooth muscle (cats, rabbits).