Functional characterization of chronic unilateral glomerulonephritis in the dog.

Functional characterization of chronic unilateral glomerulonephritis in the dog. Maintenance of appropriate balance between glomerular and tubular function in the chronically diseased kidney with primary interstitial involvement has provided the basis for the intact nephron hypothesis. In order to determine if a similar functional pattern exists in kidneys with primary glomerular disease, we developed a split-bladder dog model with unilateral nephrotoxic nephritis, the contralateral kidney serving as a control and maintaining a nonuremic environment. Baseline diseased kidney (DK)/control kidney (CK) functional indexes in ten dogs with pathologic changes of severe, chronic unilateral glomerulonephritis were as follows: glomerular filtration rate (GFR), 7.0/63 ml/min; clearance of para-aminohippuric acid (C PAH ), 30.1/228 ml/min; filtration fraction, 25.2/ 30.6% (P Na ), 0.87/0.44% (P>0.05). Maximum tubular secretory capacity of PAH/GFR and reabsorptive capacity of glucose per GFR were equal for both kidneys despite morphologic evidence of generalized glomerular involvement in the DK. In addition, following removal of CK and evolution of uremia, DK function underwent alterations qualitatively similar to those observed in previous experimental models utilizing nonglomerular disease. Thus, in the presence of experimentally induced glomerulonephritis, DK residual nephrons maintain the capacity to modulate tubular function in relation to GFR in the nonazotemic state and are capable of resetting this balance as an adaptation directed toward maintaining homeostasis in the presence of azotemia. Caracterisation fonctionnelle du rein de chein atteint de glomerulonephrite unilaterale experimentale. Le maintien d'une balance adequate entre les fonctions glomerulaires et tubulaires du rein atteint de facon chronique de lesions interstitielles a fourni la base de l'hypothese du nephron intact. Pour apprecier l'existence de modalites fonctionnelles semblables dans les reins atteints de lesions glomerulaires, nous avons developpe chez le chien un modele de vessie divisee avec nephrite toxique unilaterale. Le rein controlateral sert de controle et maintients un environnement non uremique. Les valeurs basales du rapport rein lese (DK)/rein controle (CK) des parametres fonctionnels chez dix chiens atteints de glomerulonephrite chronique unilaterale avec modifications pathologiques importantes etaient: GFR, 7,0/63 ml/min; C PAH , 30,1/228 ml/min; fraction filtree, 25,2/30,6% (P Na , 0,87/0,44% (P>0,05). La capacite maximale de secretion PAH/GFR et la capacite de reabsorption de glucose ramenee au debit de filtration glomerulaire etaient egales dans les deux reins en depit de la preuve morphologique de l'atteinte glomerulaire generalisee dans DK. De plus, apres l'ablation de CK et l'evolution de l'uremie, la fonction de DK a subi des alterations qualitatives semblables a celles observees dans les modeles precedents qui utilisaient des affections non glomerulaires. Ainsi, en presence d'une glomerulonephrite experimentale, les nephrons residuels de DK conservent la capacite de moduler la fonction tubulaire en fonction du debit de filtration glomerulaire au cours de l'etat non azotemique et sont capables de reajuster cette balance de facon adaptative dirigee vers le maintien de l'homeostasie en presence de l'uremie.