Species specificity of guinea pig erythropoietin

Various stimuli (hypoxic hypoxia, bleeding, carbon monoxide hypoxia and cobalt administration), well known to increase erythropoietin plasma level in many species including man, failed to increase the erythropoietin activity in plasma of guinea pigs when measured in the polycythaemic mice assay. Nevertheless, the plasma of these guinea pigs stimulated the erythropoiesis in polycythaemic guinea pigs which, however, failed to respond to rat erythropoietin. From this it was concluded that not only the erythropoietin, but also the erythropoietin responsive cells in the bone marrow of guinea pigs are species specific. Bilateral nephrectomy in guinea pigs exposed to hypoxia prevented the increase in the erythropoietin plasma level, thus suggesting that, similarly as in other species, also in guinea pigs the kidney is the main organ of erythropoietin elaboration. The species specificity of guinea pig erythropoietin - erythropoiesis system is an interesting exception among mammals, since the erythropoietin of a large number of species belonging to this class was demonstrated to lack species specificity.