Serum somatomedin activity measured as sulphation factor in peripheral, hepatic and renal veins of mongrel dogs: basal levels.

Serum somatomedin (SM) activity measured as sulphation factor on chick embryo cartilage was determined in peripheral (PV), hepatic (HV) and renal (RV) veins or 36 mongrel dogs. Mean SM activity +/- SEM was 0.53 +/- 0.03 U/ml in peripheral and hepatic veins, and 0.61 +/- 0.04 U/ml in renal vein (P less than 0.005). When the gradient of SM activity in hepatic or renal vein to that in peripheral vein, [HV]-[PV] or [HV]-[PV], was plotted versus SM activity in peripheral blood [PV], a negative correlation was found in the case of hepatic but not of renal blood. These data indicate that the kidney may be a production site of SM activity, whereas the liver is differently implicated in the overall regulation of SM activity.