OSMOTIC AND IONIC HOMEOSTASIS IN SOME INSECTS AND VERTEBRATES UNDER EXTREME INFLUENCES ON WATER AND SALT EXCHANGE

Dehydration, accompanied by a body mass loss of about 10% in frogs and pigeons, led to a corresponding increase in osmolality and sodium ion concentration in the blood serum. In rats these increases did not exceed 2% under analogous conditions due to the efficiency of renal function. In nettle caterpillars, whose hemolymph contains predominantly organic osmotica and potassium ions, osmolality of the carbohydrate decreased somewhat despite dehydration and weight loss, while cation concentration did not change significantly. Injection of rats and caterpillars with hyperosmotic solution showed that these animals, belonging to diverse phylogenetic branches, possess highly efficient physiological mechanisms for ionic and osmotic homeostasis.