The effect of exercise on the venous blood ammonium concentration in man.

Mild muscular exercise did not cause any significant rise in the ammonium concentration of venous blood draining the exercising forearm of control subjects or patients with cirrhosis. However, in both cirrhotic and non-cirrhotic subjects moderate exercise produced significant increases in venous blood ammonium values and these occurred earlier and were more prolonged in cirrhotic patients. Severe exercise caused larger increases in venous blood ammonium concentration in all subjects but there were no significant differences between the mean ammonium concentrations of the cirrhotic and control groups either before or after exercise. All ammonium values returned to their pre-exercise levels within half an hour of resting. The exact mechanism of these phenomena is not fully understood but they are of practical importance in the study of blood ammonium metabolism in normal subjects and in patients with cirrhosis of the liver. The importance of making subjects rest for at least 30 minutes before obtaining blood for ammonium determination is emphasized in order to obviate misleadingly high readings due to muscular activity.