High Blood Potassium in Insects in Relation to Nerve Conduction

Abstract

THE analyses of Bishop¹, Boné², Brecher³, Drilhon⁴, Tobias⁵, and others show that in phytophagous insects the potassium concentration in the hæmolymph is always high and exceeds 70 mM/litre in some instances. Such values would depolarize vertebrate or crustacean nerve fibres and stop conduction⁶. Insect nerves may have different properties in regard to potassium, or this may be bound in some way to the organic constituents of the blood. Alternatively⁷, the fibres may be protected from the high blood potassium by a sheath capable of ionic regulation, providing the axons with a local environment containing a lower potassium concentration than that of the blood.