Impact of nephron number dosing on cardiorenal damage and effects of ACE inhibition

Evaluation of potential long-term changes in endothelial functions and basic echocardiographic parameters in unilateral nephrectomy patients

AIM

Decreased nephron count may result in lower glomerular filtration rate (GFR) and cardiorenal injury in the absence of compensatory hyperfunction. In this study, we aimed to evaluate long-term effects of 50% nephron loss on endothelial functions and cardiac morphology in nondonor nephrectomy patients.

METHODS

This study comprised 26 patients (median age: 44 [37.5-50] years, male: 14) with unilateral nephrectomy and 25 healthy controls (median age: 47 [42-50] years, male: 9). Echocardiography was performed in all patients. Endothelial function was examined by measuring ischemia-induced flow-mediated dilation (FMD) of the brachial artery.

RESULTS

The mean nephrectomy time was 12.5 (8.75-23.25) years. Estimated glomerular filtration rate (eGFR [CKD-EPI]) was significantly lower in the patient group than controls (85.54±16.27 vs 96.35±11.68 mL/min, P=0.009). Uric acid levels were significantly higher in the patient group than controls (5.7±1.3 vs 4.5±0.8, P<0.001). Percentage of FMD was significantly lower in the unilateral nephrectomy patients than the control group (11.6±6.2 vs 16.1%±7.9%; P=0.029). Left ventricular posterior wall thickness (LVPWT) (P<0.001), interventricular septal thickness (IVST) (P<0.001), left ventricular (LV) mass (P=0.014), and left ventricular mass index (P=0.014) were significantly higher in the patient group.

CONCLUSION

In conclusion, 50% decrease in nephron mass due to unilateral nephrectomy may result in decreased eGFR, impaired endothelial functions and cardiac hypertrophy. What triggers endothelial dysfunction and cardiac hypertrophy in the event of mild decrease in GFR when creatinine has not been elevated yet remains unclear, but uric acid may be playing a role in this process necessitating large-scaled studies.

Cardiovascular-renal changes after kidney donation: one-year follow-up study

BACKGROUND

Long-term consequences of kidney donation are not well known. Most of the studies published were focused on renal risk. In this prospective study, we investigated the changes in cardiovascular function after kidney donation.

METHODS

Thirty-eight living kidney donors were included. In addition to 24-hr ambulatory blood pressure monitoring, serum interleukin-6, vascular cell adhesion molecule (VCAM), and asymmetric dimethylarginine levels were measured. Endothelial function was examined by measuring ischemia-induced flow-mediated dilation (FMD) of the brachial artery. All studies were repeated at 3 months and 12 months after kidney donation.

RESULTS

The mean serum interleukin-6 levels, both at 3 months and 12 months, were significantly increased as compared to the baseline (P = 0.007 and P < 0.001, respectively). The mean serum asymmetric dimethyl-arginine (P < 0.001) and VCAM levels (P < 0.001) at 12 months were significantly increased as compared to baseline. FMD values at 1 year (9.3% ± 7.1%) were significantly decreased as compared to 3 months (13.0% ± 6.0%, P = 0.001) and baseline (13.9% ± 6.3%, P = 0.002). In multivariate analysis, serum uric acid (P = 0.001), estimated glomerular filtration rate (P = 0.027), and VCAM (P = 0.014) levels were the independent predictors of FMD 12 months after kidney donation.

CONCLUSION

Our findings suggest that kidney donation might increase the cardiovascular risk in kidney donors.

Cardiorenal protection in experimental hypertension with renal failure: comparison between vasopeptidase inhibition and angiotensin receptor blockade

OBJECTIVE

The aim of the present study was to compare the preventive impact of treatment with a vasopeptidase inhibitor (VPI) with an angiotensin-receptor blocker (ARB) on left ventricular (LV) function and renal damage in rats with renal failure after 5/6 renal ablation (Nx).

METHODS

Rats (n = 15-20, each group) underwent either sham-operation (Sham) or 5/6 renal ablation (Nx). Two additional groups of Nx-animals (groups Nx-VPI and Nx-ARB) were treated with the VPI ilepatril (AVE7688, 30 mg kg(-1) d(-1)) or with the ARB olmesartan (10 mg kg(-1 )d(-1)). Animals were followed for 4 weeks.

RESULTS

Systolic blood pressure (SBP), LV hypertrophy (LVH) and LV end-diastolic pressure (LVEDP) were increased 4 weeks after Nx (p < 0.05). LV pressure rise (+dP/dt/LVPmax), LV pressure fall (-dP/dt/LVPmax), and creatinine clearance decreased, while albuminuria and renal glomerulosclerosis index (GSI) increased with Nx (p < 0.05, respectively). In comparison to Nx, treatment with both VPI and ARB normalized SBP, LVH, LVEDP, +dP/dt/LVPmax, and -dP/dt/LVPmax to Sham control levels. GSI, but not creatinine clearance, was also normalized in response to both treatments. The significant increase in albuminuria observed in Nx (+230-fold versus Sham, p < 0.0001) was partially reduced in Nx-VPI (+47-fold versus Sham, p < 0.0001) and fully abolished in Nx-ARB.

CONCLUSIONS

Both ilepatril and olmesartan conferred strong cardiorenal protective effects in rats with renal failure. While cardioprotection was clearly comparable with both treatment regimens, the ARB provided a better protection against the increase in albuminuria, although renal function and structural kidney changes were similarly affected by the VIP and ARB.

Advances in pathogenesis and current therapeutic strategies for cardiorenal syndrome

Cardiorenal syndrome (CRS) is characterized as a syndrome involving both the cardiovascular system and kidneys. Due to its complexity and high mortality, it has becoming a significant burden and a universal clinical challenge to society worldwide. The mechanisms underlying CRS are potentially multifactorial, including hemodynamic alterations, neurohormonal activation, inflammation, oxidative stress, iron disorders, anemia, and mineral metabolic derangements. Despite the understanding and awareness of CRS gaining attention, appropriate approaches to manage CRS remain deficient. Loop diuretic and thiazides, inhibition of the renin-angiotensin system, vitamin D receptor activation and dopamine and natriuretic peptides could potentially be helpful to improve the prognosis of CRS. Ultrafiltration might be an alternative therapeutic strategy for the loss of liquid. However, adenosine receptor antagonists do not appear to be superior to furosemide in CRS treatment. novel therapeutic approaches should be explored.

Subclinical nephrosclerosis is linked to left ventricular hypertrophy independent of classical atherogenic factors

Recently, cardio-renal interactions have been considered to be important and it has been demonstrated that mild renal dysfunction is associated with left ventricular hypertrophy (LVH). However, the correlation between LVH and subclinical renal damage is unclear. We investigated this association by assessing pretransplant biopsies from living kidney donors with normal renal function. We retrospectively categorized 238 living kidney donors into tertiles according to the percentage of global glomerulosclerosis (%GGS) observed in pretransplant biopsies (low, 0-3.45% (n=80); moderate, 3.46-11.76% (n=78); high, ⩾11.77% (n=80)) to analyze trends in their left ventricular mass index (LVMI) measured by echocardiography and baseline factors. LVH was defined as LVMI >110 g m(-2) in female and >125 g m(-2) in male subjects. We used a logistic regression model to evaluate any correlations between %GGS and LVH. LVMI increased significantly with increasing tertiles of %GGS, as did the prevalence of left ventricular remodeling and LVH. According to multivariate logistic regression analysis, subjects with high %GGS tertiles had a sevenfold greater risk of LVH than did those with low tertiles, even after adjusting for age, sex, systolic blood pressure, history of diabetes mellitus, total serum cholesterol and glomerular filtration rate (GFR) measured by a radioisotopic technique. There is an association between GGS and LVH in subjects with normal renal function. This association is significant after adjustment for age, sex, blood pressure, GFR and other atherogenic factors.

Genetic low nephron number hypertension is associated with altered expression of osteopontin and CD44 during nephrogenesis

AIMS

The study set out to investigate whether the osteopontin (OPN)-CD44-integrin-receptor-system is differently regulated during nephrogenesis in inborn nephron deficit, a major determinant of human primary hypertension and cardiovascular disease in adult life.

METHODS

We compared a genetic rat model with an inherited nephron deficit, the Munich-Wistar-Froemter rat (MWF), to normotensive Wistar rats during nephrogenesis at day 19 of fetal development (E19) and at postpartal day 7 (D7).

RESULTS

Renal OPN mRNA (-75%, P<0.05) and protein expression (-38%, P<0.05) were strongly decreased at E19 in MWF compared to Wistar. Renal mRNA-expression of CD44 was increased at E19 in MWF (+271%, P<0.05). At D7, renal OPN protein expression was increased (+115%, P<0.05) and renal mRNA-expression of CD44 remained elevated compared to Wistar control (+127%, P<0.05).

CONCLUSIONS

Altered fetal expression of the OPN-CD44-integrin-receptor-system in the MWF model points to a possible role in low nephron number hypertension and cardiovascular disease.