Effect of adrenergic drugs on the lantern of the larval Photuris firefly.

Smalley (1965) confirmed and extended the original observations of Kastle & McDermott (1910) that norepinephrine induces glowing in the lantern of the adult firefly. She further conclusively demonstrated that normal neural excitation involved an adrenergic rather than a cholinergic transmitter. Amphetamine apparently induced luminescence by causing the nerve endings to release their transmitter. Reserpine, a drug known to drain vertebrate nerve ends of adrenergic transmitters, abolished luminescence associated with neural stimulation. The ability of the lantern to produce a long-latency 'slow flash' or a short-latency 'quick flash', first reported by Buck, Case & Hanson (1963), was used to distinguish between the presence of transmitter in the nerve endings or its loss. Extracts of the lantern were tested for activity on rat uterus and colon and their effects were found to be intermediate between those of epinephrine and norepinephrine. The paired lanterns of the larval firefly, Photuris sp., also respond to adrenergic agents. They represent a simpler structural system compared to the adult because electron micrographs show that the nerves terminate directly on the photocytes (M. Wetzel, unpublished). Further, the lantern can be extirpated, immersed in an oxygenated saline solution, tested with various drugs and its luminescent response can be monitored with some precision. This procedure has allowed us to study the pharmacological actions of various drugs and other chemical agents on this luminescent system in vitro. MATERIALS AND METHODS