Angiotensin II receptor blocker pretreatment of rats undergoing sudden renal ablation

The Intrarenal Renin-angiotensin System Is Activated Immediately after Kidney Donation in Kidney Transplant Donors

Objective The intrarenal renin-angiotensin system (RAS) is activated in clinical settings, such as chronic kidney disease (CKD), as well as in CKD animal models, and kidney transplant donors have a greater risk of end-stage renal disease than healthy controls. However, whether or not the intrarenal RAS is activated immediately after kidney donation in kidney transplant donors is unclear, and the mechanism underlying intrarenal RAS activation is unknown. Methods We investigated 10 kidney transplant donors (4 men and 6 women, 58.6±9.0 years of age). Their blood pressure (BP), estimated glomerular filtration rate (eGFR), plasma angiotensinogen (AGT) and plasma angiotensin II (AngII) levels (which reflect circulating RAS activation), urinary albumin excretion, and urinary AGT excretion (which reflects intrarenal RAS activation) were evaluated before kidney donation (-1.2±0.40 days) and after kidney donation (7.5±1.7 days). Results The renal function after kidney donation was significantly lower than before donation. There were no significant differences in the BP during 24-h ambulatory BP monitoring, plasma AngII levels, or urinary albumin excretion after kidney donation. In contrast, the levels of plasma AGT and urinary AGT excretion were significantly increased after kidney donation. The urinary AGT excretion after kidney donation did not show a significant relationship with the systolic BP, plasma AGT, plasma AngII, or urinary albumin excretion. In addition, the percentage change in urinary AGT excretion after kidney donation was not associated with the percentage change in other clinical parameters. Conclusion The intrarenal RAS is activated in kidney transplant donors immediately after kidney donation, independent of the systemic BP and filtration of increased plasma AGT, due to augmented inflammation.

The Effects of Unilateral Nephrectomy on Blood Pressure and Its Circadian Rhythm

Objective Hypertension and diurnal blood pressure (BP) variation are widely accepted as risk factors for renal damage. However, the effects of unilateral nephrectomy on BP and its circadian rhythm have not yet been clarified in patients with a compromised renal function, including dialysis patients. Methods We investigated 22 unilateral nephrectomized patients (16 men and 6 women, age: 64.5±14.3 years). The function of the circulating renin-angiotensin system (RAS) (plasma renin activity and plasma angiotensin II) and 24-h ambulatory BP monitoring (ABPM) were evaluated before and after nephrectomy. Daytime and nighttime 24-h ABPM values were determined based on sleep and waking times. Results In non-dialysis patients, the estimated glomerular filtration rate after nephrectomy was significantly lower than that before (before, 62.4±23.2 mL/min/1.73 m² vs. after, 43.7±16.8 mL/min/1.73 m²; p<0.01). No significant differences were noted in the levels of BPs and circulating RAS before and after nephrectomy. However, the night-to-day (N/D) ratio of systolic BP (SBP) was significantly higher after nephrectomy than before (before, 93.3±6.5% vs. after, 98.4±6.9%; p<0.01), and the patterns of circadian BP rhythm also significantly differed before and after nephrectomy (p=0.022). Namely, the rates of dipper patterns decreased and nondipper and riser patterns increased after nephrectomy. In contrast, in dialysis patients, no significant differences were observed in the N/D ratio of SBP or the patterns of circadian BP rhythm before and after nephrectomy. Conclusion Unilateral nephrectomy affects the circadian rhythm of BP but not absolute values of BP.