The influence of concomitant experimental hypertension and glomerulonephritis

Utilizing the two kidney-one clip Goldblatt model (CH), we have examined the influence of hypertension upon the course of antiglomerular basement membrane antibody-induced glomerulonephritis (GN) over a period of 10 to 14 weeks after induction of CH and GN, utilizing evaluations in the awake rat by renal micropuncture of the unclipped kidney and morphologic analysis (control [C], GN, CH, and GN+CH). Metabolic studies revealed that GN and GN+CH rats developed proteinuria, elevations in serum creatinine and blood pressure (P less than 0.05). GN+CH resulted in significant reductions in two kidney glomerular filtration rate (GFR) below values in C, and GFR in the unclipped kidney was markedly reduced when compared to CH. The glomerular capillary hydrostatic pressure and the pressure gradient( (delta P) were elevated approximately 4 to 5 mm Hg in GN and CH rats and 6 mm Hg above GN and CH values in the GN+CH rats. The glomerular ultrafiltration coefficient (LpA) was reduced to approximately 40% of C in both GN and GN+CH in spite of further increases in delta P. Surface nephron filtration rate was similar in all groups, suggesting glomerular dysfunction was primarily in nephrons below the surface in GN+CH. Morphologic evaluation revealed that GN+CH exhibited a combination of diffuse and focally sclerotic lesions characteristic of GN and CH, respectively. Documented further increases in PG did not worsen glomerular morphology, but kidney GFR did decrease. Hypertension induced deterioration of glomerular function in nephrons below the surface was not associated with marked morphologic deterioration, but a combination of the characteristics of GN and CH.