Associations between sympathetic activity, plasma concentrations of renin, aldosterone, and parathyroid hormone, and the degree of intractability of blood pressure control in modialysis patients

Effect of parathyroid hormone on cardiac function in rats with cardiomyopathy

The present study investigated the role of parathyroid hormone (PTH) in non-ischemic cardiomyopathy (CM) and its underlying mechanism. A total of 30 Sprague-Dawley male rats were randomly divided into a control group (n=6) and an experimental group (n=24). To induce CM in the rats of the experimental group, 2 mg/kg Adriamycin (ADR) was administered intraperitoneally with 5 equal injections every third day followed by 5 weekly injections resulting in a cumulative dose of 20 mg/kg. Following establishment of the model, rats in the experimental group were subdivided into a PTH-untreated CM group that received daily normal saline subcutaneous injections for 7 days and three treated CM groups that received daily subcutaneous injections of 5, 10, or 20 µg/kg of recombinant PTH for 7 days. Rats in the control group accordingly received intraperitoneal and subcutaneous injections of normal saline. Blood sample analysis revealed that B-type natriuretic peptide (BNP), troponin T, C-reactive protein (CRP), creatinine and phosphorus concentrations were increased in the PTH-untreated CM group compared with that in the control group, whereas PTH and calcium concentrations were decreased. Administration of PTH dose-dependently decreased BNP, CRP, creatinine and phosphorus levels, and increased PTH and calcium levels. Notably, there were significant differences in PTH, BNP, troponin T, CRP, creatinine, calcium, and phosphorus levels among the rats in the five groups (P<0.01). Cardiac ultrasonography results indicated that the left ventricular ejection fraction (LVEF) was significantly decreased in rats treated with ADR compared with the rats from the control group (P<0.01). However, the LVEF gradually recovered with elevated PTH treatment doses. The overall differences of LVEF and left ventricular end-systolic volume in the five experimental groups were statistically significant (P<0.01). Furthermore, there were dose-dependent increases in LV mass and left ventricular end-diastolic volume in PTH-treated rats; however, the differences between any two groups did not reach statistical significance (P>0.05). Immunohistochemical staining and western blot analysis using an anti-PTH polyclonal antibody was performed to evaluate the protein expression levels of PTH in myocardial tissues. The mRNA expression levels of PTH and BNP were measured using reverse transcription-quantitative polymerase chain reaction. The results demonstrated that the mRNA and protein expression levels of PTH in myocardial tissues were significantly decreased in ADR-treated rats compared with the levels in the control group rats. Injection of recombinant PTH significantly increased PTH expression and reduced BNP expression in dose-dependent manners (P<0.05). These findings demonstrated that PTH can improve cardiac function in rats with ADR-induced CM, suggesting a potential therapeutic application for PTH in non-ischemic CM.

The association between left ventricular hypertrophy and biomarkers in patients on continuous ambulatory peritoneal dialysis

Background and Objectives

Left ventricular hypertrophy (LVH) is a major cardiovascular complication and an important predictor of mortality in patients with end stage renal disease. Some studies have shown that the serum aldosterone levels are correlated with LVH in non-diabetic patients undergoing hemodialysis. The objective of this study was to elucidate the relationships between serum biomarkers, including aldosterone, and echocardiographic findings, such as LVH, in patients on peritoneal dialysis.

Subjects and Methods

Thirty patients on continuous ambulatory peritoneal dialysis (CAPD) for >12 months at Soonchunhyang University Cheonan Hospital were included. Transthoracic echocardiography was performed and the left ventricular mass index (LVMI) was calculated using the Devereux formula. Serum biomarkers {N-terminal pro B-type natriuretic peptide (NT-proBNP), troponin T, C-reactive protein, renin, and aldosterone} were measured.

Results

Sixteen of 30 patients had LVH on the basis of the LVMI. The mean serum aldosterone level was 62.53±60.73 pg/mL (range, 5.03-250.68 pg/mL). LVH, on the basis of the LVMI, was not correlated with the serum aldosterone level. The serum aldosterone levels were not associated with echocardiographic findings, even with co-existing diabetes mellitus. The LVMI had a negative correlation with the hemoglobin (r=-0.405, p=0.029) and hematocrit (r=-0.374, p=0.042), and a positive correlation with NT-proBNP (r=0.560, p=0.002). The other biomarkers (renin, aldosterone, troponin T, and C-reactive protein) were not correlated with the LVMI. The LVMI was correlated with the left atrium volume index (r=0.675, p<0.001).

Conclusion

NT-proBNP is a good marker to predict LVH in patients undergoing CAPD. The serum aldosterone level is not correlated with LVMI, even with co-existing diabetes mellitus.