Low Plasma Hydrogen Sulfide Is Associated with Impaired Renal Function and Cardiac Dysfunction

Abstract

Background: Chronic kidney disease (CKD) has been proposed to associate with decreased hydrogen sulfide (H2S) level. Nevertheless, the role of H2S in the pathogenesis of CKD has not been fully investigated. Our study aimed to investigate the plasma level of endogenous H2S in patients with different stages of CKD, and to identify the role of H2S in the progression of CKD and its relationship with cardiovascular diseases. Methods: A total of 157 non-dialysis CKD patients were recruited in our study, with 37 age- and sex-matched healthy individuals as control. Plasma concentration of H2S was measured with spectrophotometry. Sulfhemoglobin, the integration of H2S and hemoglobin, was characterized and measured by dual wavelength spectrophotometry. Serum levels of homocysteine (Hcy), cardiac troponin T (cTnT), and N-terminal pro B type natriuretic peptide were measured using automated analyzers. Conventional transthoracic echocardiography was performed and left ventricular ejection fraction (LVEF) was analyzed as a sensitive parameter of cardiac dysfunction. Results: The plasma H2S level (μmol/L) in CKD patients was significantly lower than those in healthy controls (7.32 ± 4.02 vs. 14.11 ± 5.24 μmol/L, p < 0.01). Plasma H2S level was positively associated with estimated glomerular filtration rate (eGFR; ρ = 0.577, p < 0.01) and negatively associated with plasma indoxyl sulfate concentration (ρ = –0.554, p < 0.01). The mRNA levels of cystathionine β-synthase and cystathionine γ-lyase, 2 catalytic enzymes of H2S formation, were significantly lower in blood mononuclear cells of CKD patients with respect to controls; however, the mRNA level of 3-mercaptopyruvate sulfurtransferase, as another H2S-producing enzyme, was significantly higher in CKD patients. The serum concentration of Hcy, acting as the substrate of H2S synthetase, was higher in the CKD group (p < 0.01). Specifically, the content of serum Hcy in CKD stages 3–5 patients was significantly higher than that in CKD stages 1–2, indicating an increasing trend of serum Hcy with the decline of renal function. Examination of ultrasonic cardiogram revealed a negative ­correlation between plasma H2S level and LVEF (ρ = –0.204, p < 0.05) in CKD patients. The H2S level also correlated negatively with cTnT concentration (ρ = –0.249, p < 0.01). Conclusions: Plasma H2S level decreased with the decline of eGFR, which may contribute to the cardiac dysfunction in CKD ­patients.