The study investigates the effects of angiotensin I converting enzyme (ACE) inhibition with enalapril on glomerular hypertension and injury in rats with reduced renal mass. Four groups of male Munich-Wistar rats underwent 5/6 nephrectomy, with groups 2 and 4 receiving enalapril treatment. Micropuncture studies showed that enalapril prevented systemic hypertension and maintained glomerular transcapillary hydraulic pressure gradient at near-normal levels without significantly compromising glomerular filtration rate. Eight weeks after nephrectomy, enalapril-treated rats had normal blood pressure, reduced proteinuria, and less glomerular injury compared to untreated rats. These findings suggest that controlling glomerular hypertension limits glomerular injury in rats with reduced renal mass. The study supports the idea that glomerular hemodynamic changes mediate progressive renal injury when nephron number is reduced. Enalapril treatment prevented glomerular capillary hypertension, which slowed the progression of glomerular injury. The study also highlights the importance of controlling systemic and glomerular hypertension in patients with renal disease to prevent glomerular damage.The study investigates the effects of angiotensin I converting enzyme (ACE) inhibition with enalapril on glomerular hypertension and injury in rats with reduced renal mass. Four groups of male Munich-Wistar rats underwent 5/6 nephrectomy, with groups 2 and 4 receiving enalapril treatment. Micropuncture studies showed that enalapril prevented systemic hypertension and maintained glomerular transcapillary hydraulic pressure gradient at near-normal levels without significantly compromising glomerular filtration rate. Eight weeks after nephrectomy, enalapril-treated rats had normal blood pressure, reduced proteinuria, and less glomerular injury compared to untreated rats. These findings suggest that controlling glomerular hypertension limits glomerular injury in rats with reduced renal mass. The study supports the idea that glomerular hemodynamic changes mediate progressive renal injury when nephron number is reduced. Enalapril treatment prevented glomerular capillary hypertension, which slowed the progression of glomerular injury. The study also highlights the importance of controlling systemic and glomerular hypertension in patients with renal disease to prevent glomerular damage.