Effect of Potassium Chloride on the Normal and Denervated Iris

Abstract

Camp and Higgins 1 have called attention to the similarity of the actions of epinephrin and the potassium salts on various organs and have advanced the hypothesis that epinephrin acts by liberating potassium; no reference was made by them to the action of potassium on the iris.

Experiments were carried out using intact and excised bulbi of frogs and intact normal and denervated eyes of living rabbits. Forty-four excised frog bulbi placed in 0.6% KCl, and observed 90 to 150 minutes, resulted in 32 constrictions, 1 dilation, and 11 showing no change. Control eyes placed in 0.6% NaCl gave similar results.

In another sseries of experiments, the cerebra of frogs were pithed or lightly crushed and 0.25 to 1 cc 0.6% KCl injected intracardially or into the aorta. Of 66 eyes observed, 18 showed no change; 41 constricted and 7 dilated. The dilatations were slight or moderate, the maximum being 1 mm. Control injections of 0.6% NaCl produced constriction or no change.

Large doses of KCl, i. e., 1 to 2 cc of a 4.0% solution injected intraärterially into 12 frogs produced constriction in all cases. During the constricted state 0.25 to 0.5 cc epinephrin 1:10,000 was injected intracardially or into the aorta; in all cases the pupils markedly dilated.

Seventeen excised bulbi from frogs previously injected with 1-2 cc 1.0% KCl showed no greater sensitivity to dilute solution of epinephrin than 18 control eyes from frogs injected with similar amounts of NaCl.

Three series of experiments were carried out on living rabbits having one iris sympathectomized, by removing the superior cervical ganglion.

In the first series, 11 experiments on 6 rabbits, 1.0 cc of a 4.1% solution of NaCl was injected subconjunctivally in both eyes. There were no changes except for a few transitory constrictions.