Evidence for renal vascular remodeling in angiotensin II-induced hypertension.

OBJECTIVES: To determine whether 'slow pressor' hypertension from systemic angiotensin (Ang II) infusion was associated with renal vascular structural remodeling of the renal resistance vessels and glomerulus. METHODS: Ang II (4.5-10 ng/kg per min) or vehicle was infused for 10 days. Renal resistance vascular lumen changes were assessed at 10 days as changes in renal pressure flow and pressure-glomerular filtration rate (GFR) and pressure-Na+ excretion in maximally dilated, isotonically perfused kidneys. RESULTS: Low-dose, initially subpressor Ang II infusion for 10 days increased conscious arterial pressure by 27 mmHg compared to vehicle-infused rats (140 +/- 7 and 113 +/- 2 mmHg, respectively). There was no change in the pressure-flow relationship but the slope of the pressure-GFR relationship was reduced in the rats treated with Ang II. These changes are consistent with equal and opposite pre-and post-glomerular effects (i.e., increased pre-glomerular vessel resistance and reduced post-glomerular vessel resistance) and reduced glomerular ultrafiltration coefficient. There was also a significant reduction in pressure-dependent Na+ excretion. CONCLUSIONS: Slow pressor Ang II-induced hypertension was associated with apparent pro-hypertensive changes in the kidney involving pre/post-glomerular vessel remodeling as indicated by an apparent reduction in pre-glomerular lumen dimensions, a reduced glomerular filtration capacity and a reduction in the pressure natriuresis relationship.