Inositol pentaphosphate in fish red blood cells

Abstract

Inositol pentaphosphate (IP5) has long been characteristic of avian erythrocytes. We now report that this compound is also present in the red cells of two species of elasmobranch fishes, Squalus acanthias (spiny dogfish) and Narcacion nobiliana (torpedo ray). The mean concentration of I5 is 0.36 and 0.24 micromoles per ml of red cells respectively. ATP is the major organic phosphate in both fishes. 2.3-diphosphoglycerate is absent and GTP levels correspond approximately to the levels of I5.