Krivosíková Z, Spustová V, Dzúrik R
Institute of Preventive and Clinical Medicine, Department of Clinical Pharmacology, Bratislava, Slovak Republic.
Physiol Res. 1998;47(3):177-83.
The key regulatory enzymes of kidney ammoniagenesis appear to be P-dependent (PDG) and P-independent (PIG) glutaminases. While the participation of PDG has been satisfactorily elucidated, the significance of PIG remains doubtful. Rat kidney cortex slices synthesized ammonia even under basal conditions. Metabolic acidosis, hippurate and insulin stimulated ammonia production. Under basal conditions, PDG activity in kidney homogenate, was twice as high as PIG activity. Metabolic acidosis stimulated ammonia production by the stimulation of both PDG (100%) and PIG (57%) activities. Hippurate stimulated only PIG activity both under basal conditions (90%) and in metabolic acidosis (52%), while it inhibited PDG activity only insignificantly under basal conditions and markedly (53%) in metabolic acidosis. Insulin stimulated both PIG and PDG activities under basal conditions as well as in metabolic acidosis and potentiated the PIG stimulation by hippurate while it potentiated the hippurate inhibition of PDG both under basal conditions and in acidotic rats. In conclusion, both PDG and PIG participate in ammoniagenesis and are stimulated by metabolic acidosis and insulin. Hippurate stimulates PIG, while it inhibits PDG in metabolic acidosis and even after insulin administration. The effect of hippurate appears to be of physiological interest.
肾脏氨生成的关键调节酶似乎是磷酸依赖性（PDG）和磷酸非依赖性（PIG）谷氨酰胺酶。虽然PDG的参与已得到令人满意的阐明，但PIG的重要性仍存疑问。大鼠肾皮质切片即使在基础条件下也能合成氨。代谢性酸中毒、马尿酸盐和胰岛素可刺激氨的产生。在基础条件下，肾脏匀浆中的PDG活性是PIG活性的两倍。代谢性酸中毒通过刺激PDG（100%）和PIG（57%）的活性来刺激氨的产生。马尿酸盐在基础条件下（90%）和代谢性酸中毒时（52%）仅刺激PIG活性，而在基础条件下对PDG活性的抑制作用不明显，在代谢性酸中毒时则显著（53%）。胰岛素在基础条件下以及代谢性酸中毒时均刺激PIG和PDG活性，并增强马尿酸盐对PIG的刺激作用，同时在基础条件下以及酸中毒大鼠中增强马尿酸盐对PDG的抑制作用。总之，PDG和PIG均参与氨生成，并受到代谢性酸中毒和胰岛素的刺激。马尿酸盐刺激PIG，而在代谢性酸中毒时以及给予胰岛素后抑制PDG。马尿酸盐的作用似乎具有生理学意义。
