Loss of nitrogen from organs in rats induced by exogenous glucagon

Rats weighing 220 g were injected sc with zinc protamin glucagon 20 micrograms once daily (recurrent hyperglucagonemia) and zinc protamin glucagon 60 micrograms three times daily (chronic hyperglucagonemia); the controls received the vehicle three times daily. In the first group blood glucagon rose to above 200 ng/liter for 5 h every day; in the second group it constantly stayed above 600 ng/liter. After both 2 (n = 5) and 14 (n = 5) days treatment the control total blood alpha-amino-nitrogen (AAN) concentration was 4.3 +/- 0.1 mmol/liter, and the urea nitrogen synthesis rate was 4.9 +/- 0.4 mumol/(min.100 g BW) (mean +/- SEM) in controls. In recurrent hyperglucagonemic rats, treated for both 2 (n = 5) and 14 (n = 5) days, total AAN was 3.6 +/- 0.2 mmol/liter (P less than 0.05 vs. control) and urea nitrogen synthesis rate 4.5 +/- 0.8 mumol/(min.100 g BW). In chronic hyperglucagonemic, treated for both 2 (n = 5) and 14 (n = 5) days, total AAN was 2.2 +/- 0.1 mmol/liter (P less than 0.05 vs. control) and UNSR 7.9 +/- 0.8 mumol/(min.100g BW) (P less than 0.05 vs. control). The urea excretion was identical in controls and during recurrent hyperglucagonemia, but it was increased by 50% during chronic hyperglucagonemia. Food intake was the same in all groups. N Balances decreased from 10 mmol/24 h to 5 mmol/24 h (P less than 0.05) by chronic hyperglucagonemia. The total organ N content did not change by recurrent hyperglucagonemia, but in chronic hyperglucagonemia it decreased to 65-85% (P less than 0.01) in carcass, intestines, liver, and kidneys. In conclusion chronic but not recurrent hyperglucagonemia increases the rate of urea synthesis and decreases the blood amino acid concentration. This is suggested to be a reason for the loss of N from organs by chronic hyperglucagonemia.