Glutamine-synthesizing activity in lungs of fed, starved, acidotic, diabetic, injured and septic rats

Abstract

The maximal catalytic activity of glutamine synthetase was measured in lung homogenates of the rat (being 5.46 +/- 0.29 mumol/min per g wet wt. or 31.70 +/- 2.62 nmol/min per mg of protein at 37 degrees C, in fed animals). The activity is similar to that of liver, but 16-fold higher than that in quadriceps muscles. Chronic (NH4Cl-induced) or acute (HCl-induced) metabolic acidosis had no effects on enzyme activity, but there was a marked increase in the activity of glutamine synthetase in starved (30-40%), streptozotocin-diabetic (17%), dexamethasone-treated (18-22%), laparotomized (25-27%) and septic rats (24-45%).