[Experimental polycythemia induced by lactate in Tritons].

Specimens of Triturus cristatus carnifex (Laurenti) raised for 4 weeks in a 7 g/l solution of sodium lactate present a mean increase of about 32% in the red blood cell count in comparison to control newts raised in identically oxygenated water. Since lactate alone determines an increase in the number of erythrocytes as does hypoxia and hypoxia always induces an increase in plasma lactate levels, it can be deduced that erythropoietin (ESF) production is stimulated by an increase in plasma lactate and not directly by a lack of oxygen. The hypothesis that ESF in newts is produced by the "lactate sensitive cells" of the renal corpuscles, which hypertrophy after experimental anaemia or treatment with lactic acid salts, is indirectly confirmed.