title: [Activity of renal enzymes producing ammonia from glutamine in the absence of phosphate in the rat: 1. Effect of chronic metabolic acidosis].
abstract: Phosphate- independent glutaminase (PIG) and gamma-glutamyl transpeptidase (gamma GT) activities were evaluated in renal cortex homogenates of rats under normal acid-base balance or chronic metabolic acidosis (CMA). An incubation medium containing glutamine 2 mM, no phosphate, pH 7,40, was used. PIG activity was measured as glutamate production and total gamma GT activity as ammonia production. In normal rats gamma GT activity was significantly higher (0,84 +/- 0,05 mumol/min/g wet wt.) than PIG activity (0,48 +/- 0,06 mumol/min/g wet wt.) (p less than 0,01). In CMA there was a significant increase in PIG activity and an even higher increase in gamma GT activity (p less than 0,01 compared to controls in both cases). The glutamate production/ammonia production ratio was 0,57 +/- 0,05 in normal rats, and 0,37 +/- 0,03 in CMA ( p less than 0,025). These data suggest that the increase in PIG activity and, to a further extent, the increase in gamma GT activity may play an important role in augmenting renal ammonia production in CMA.
mesh_terms: D000138:Acidosis / Q000201:enzymology*; D000641:Ammonia / Q000378:metabolism*; D000818:Animals; D002908:Chronic Disease; D005972:Glutaminase / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D007672:Kidney Cortex / Q000201:enzymology*; D008297:Male; D010710:Phosphates / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D005723:gamma-Glutamyltransferase / Q000378:metabolism
chemical_list: D010710:Phosphates; D005973:Glutamine; D000641:Ammonia; D005723:gamma-Glutamyltransferase; D005972:Glutaminase
vernacular_title: Attività degli enzimi che producono ammoniaca dalla glutamina in assenza di fosfato nel rene di ratto: 1. effetto della acidosi metabolica cronica.