Further Investigations of the Effect of Tissues on Autonomic Drugs

Abstract

In previous papers 1 2 it was established that epinephrine and acetylcholine are destroyed by tissues (in this case the scales of Fundulus heteroclitus); it was found also that 50% deuterium oxide inhibits this destruction. Using the same technique and method of recording as previously, the destructive effect of the same tissues has now been investigated on atropine, pilocarpine, physostigmine and mecholyl.

Three kinds of solutions were made in each case: (1) solution of the drugs used, (2) the same solution + fish scales, and (3) the same solution + fish scales + 50% deuterium oxide. All solutions were tested 4 times : immediately after they had been made, 12 hours later, 24 hours later, and 48 hours later. The test objects were melanophores of isolated scales of Fundulus heteroclitus freshly removed from the fish.

A. Atropine. One-half percent solution of atropine sulphate was used; in this concentration, atropine fully expands the melanophores. The solutions of atropine sulphate to which fish scales were added showed a much slighter effect after 12 hours. After 24 and 48 hours the same solutions were ineffective. If, however, 50% deuterium oxide were added together with the scales, the atropine solution showed practically no change in effect on the melanophores after 12, 24, or 48 hours. Control solutions (pure one-half percent atropine sulphate) also showed no difference in effect during the whole experiment.

B. Pilocarpine. One-half percent solution of pilocarpine chloride was used; in this concentration pilocarpine fully expands the melanophores. There was no difference in the effect on fish melanophores between the solutions of pilocarpine without and with scales, even 48 hours after the scales had been added.

C. Physostigmine. One-half percent solution of physostigmine sulphate was used; in this concentration, physostigmine, too, expands the melanophores well.