An in vivo effect of renin on erythropoietin formation

The subcutaneous injection of a single dose of renin (2.5 Goldblatt units per 100 g body weight), i.e., approximately twice the amount present in both kidneys of a normal 200 g rat, caused a pronounced increase in the plasma concentration of erythropoietin and of angiotensinogen in rats exposed to low atmospheric pressure (0.40 atm.) as compared with saline injected hypoxic rats. Twice this amount (5.0 Goldblatt units per 100 g body weight) had no effect in animals that were kept at ambient pressure. The effect of renin on erythropoietin formation was first observed after 8 hours of hypoxia and lasted until 24 hours; the effect of renin on angiotensinogen formation was first observed after 12 hours of hypoxia and lasted until 20 hours. These results are not entirely dependent upon the presence of the kidneys. The subcutaneous injection of homologous renin (2 or 4 Goldblatt units per 100 g body weight) stimulated the formation of erythropoietin in 10 anephric rats (from a group of 12). The rats had been nephrectomized 10 hours prior to injection of the renin and then exposed to 0.40 atm. for 14 hours. Erythropoietin was not present in any of a similar group of eight anephric rats that had received injections of saline prior to the same hypoxic exposure.