The effect of eel calcitonin on calcium influx and plasma ion levels in axolotls, Ambystoma mexicanum.

Plasma total calcium and calcium influx, measured during 4-h 45Ca influx experiments, were lower in control axolotls, Ambystoma mexicanum, during August when compared to those in July. A single intraperitoneal injection of 10 micrograms of synthetic eel calcitonin significantly reduced the calcium influx rates during both months but the effect was greater in July (P less than 0.001) than in August (P less than 0.05). Plasma levels of calcium, sodium, potassium, and magnesium were not affected. In neotonous wholly aquatic amphibians, eel calcitonin may work in the same way as it does in fish by reducing the uptake of dissolved calcium from the ambient medium.