Effect of Adrenergic Drugs on the Lantern of the Larval Photuris Firefly

Abstract

1. A number of adrenergic drugs were tested for their ability to induce luminescence in the extirpated lantern of the firefly larva. The drugs produce sigmoid doseresponse curves characteristic of drug-receptor interactions when drug concentration is plotted against either maximum intensity or maximum rate of intensity rise. 2. Amphetamine and saline of high potassium concentration induce intense luminescence in freshly extirpated lanterns but act only weakly or not at all in lanterns suffering from treatment by reserpine injection 48 hr. previously. 3. No significant difference in response to norepinephrine was observed in lanterns immersed in standard saline, 0.32 M sucrose, 0.16 M choline chloride or 0.16 M-NaCl₂ but 0.107 M-CaCl₂ considerably slowed the response. 4. Some generalizations concerning structural character and effectiveness in inducing luminescence were made by comparing the drugs tested. It was not possible to describe the mode of action of the drugs. The observation, however, that solutions lacking sodium and potassium did not significantly alter the response was felt to argue against the action of the adrenergic drugs in affecting ion movement across the photocyte membrane.