Glomerular injury in uninephrectomized spontaneously hypertensive rats. A consequence of glomerular capillary hypertension

Micropuncture and/or morphologic studies were performed in intact Wistar-Kyoto rats (WKY) (group 0) intact spontaneously hypertensive rats (SHR) (groups 1 and 5), uninephrectomized (UNX) WKY (groups 2 and 6), and UNX SHR (groups 3 and 4, 7 and 8). UNX was performed when rats were 5 wk of age. Groups 0-4 were observed for 34 wk after which whole kidney clearance and morphologic studies were performed. Groups 5-8 underwent micropuncture study at 10 wk of age. Groups 4 and 8 were fed a diet containing 6 % protein. All other rats in-gested standard laboratory diet. 5 wk after UNX, normotensive group 6 had higher single nephron glomerular filtration rate (SNGFR) and initial glomerular plasma flow rate (QA) than in-tact, hypertensive group 5. Glomerular transcapillary hydraulic pressure difference (AP) was similar in these two groups. Hy-pertensive group 7 exhibited less elevation in SNGFR and QA than group 6, but AP was significantly increased. The presence of glomerular capillary hypertension in UNX SHR at 10 wk was associated with the development of significant proteinuria and an increased incidence of mesangial expansion and glomerular sclerosis at 7 mo (group 3) as compared with groups 0, 1, and 2. Protein restriction prevented the development of increased AP in UNX SHR (group 8) and also conferred long-term pro-tection from increased urinary protein excretion and glomerular injury (group 4). These studies suggest that glomerular capillary hypertension predisposes to glomerular injury in this model of hypertension with reduced renal mass