Abstract
1. The effect of ferrous iron in blocking the action of epinephrine is not specific. The action of epinephrine, eserine, cocaine and naphazoline hydrochloride is reduced or blocked by ferrous iron in three to sixty fold quantities.
2. To obtain the same effect upon the action of atropine and scopolamine much larger (300-600 fold) quantities of ferrous iron are required.
3. After sympathetic denervation the dilator smooth muscle of the iris becomes more sensitive to the action of epinephrine and the mydriatic effect can only be blocked by considerably higher doses of Fe++.
4. Mydriasis caused by the stimulation of the cervical sympathetic nerve is also inhibited by ferrous iron.
5. These results may be explained as follows: a. ferrous iron in high doses reduces the reactivity of smooth muscles; b. in smaller doses it blocks the effect of the drugs mentioned above, without exerting a direct effect.
Footnotes
- Received November 16, 1949.
- 1950 by The American Society for Pharmacology and Experimental Therapeutics
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