Endogenous Hydrogen Sulfide Enhances Carotid Sinus Baroreceptor Sensitivity by Activating the Transient Receptor Potential Cation Channel Subfamily V Member 1 (TRPV1) Channel.

BACKGROUND: We aimed to investigate the regulatory effects of hydrogen sulfide (H2S) on carotid sinus baroreceptor sensitivity and its mechanisms. METHODS AND RESULTS: Male Wistar-Kyoto rats and spontaneously hypertensive rats (SHRs) were used in the experiment and were given an H2S donor or a cystathionine-ß-synthase inhibitor, hydroxylamine, for 8 weeks. Systolic blood pressure and the cystathionine-ß-synthase/H2S pathway in carotid sinus were detected. Carotid sinus baroreceptor sensitivity and the functional curve of the carotid baroreceptor were analyzed using the isolated carotid sinus perfusion technique. Effects of H2S on transient receptor potential cation channel subfamily V member 1 (TRPV1) expression and S-sulfhydration were detected. In SHRs, systolic blood pressure was markedly increased, but the cystathionine-ß-synthase/H2S pathway in the carotid sinus was downregulated in comparison to that of Wistar-Kyoto rats. Carotid sinus baroreceptor sensitivity in SHRs was reduced, demonstrated by the right and upward shift of the functional curve of the carotid baroreceptor. Meanwhile, the downregulation of TRPV1 protein was demonstrated in the carotid sinus; however, H2S reduced systolic blood pressure but enhanced carotid sinus baroreceptor sensitivity in SHRs, along with TRPV1 upregulation in the carotid sinus. In contrast, hydroxylamine significantly increased the systolic blood pressure of Wistar-Kyoto rats, along with decreased carotid sinus baroreceptor sensitivity and reduced TRPV1 protein expression in the carotid sinus. Furthermore, H2S-induced enhancement of carotid sinus baroreceptor sensitivity of SHRs could be amplified by capsaicin but reduced by capsazepine. Moreover, H2S facilitated S-sulfhydration of TRPV1 protein in the carotid sinus of SHRs and Wistar-Kyoto rats. CONCLUSIONS: H2S regulated blood pressure via an increase in TRPV1 protein expression and its activity to enhance carotid sinus baroreceptor sensitivity.

L-cystathionine inhibits oxidized low density lipoprotein-induced THP-1-derived macrophage inflammatory cytokine monocyte chemoattractant protein-1 generation via the NF-κB pathway.

This study aimed to explore whether and how L-cystathionine had any regulatory effect on the inflammatory response in THP-1-derived macrophages cultured in vitro under oxidized low-density lipoprotein (ox-LDL) stimulation. The human monocyte line THP-1 cell was cultured in vitro and differentiated into macrophages after 24 hours of PMA induction. Macrophages were pretreated with L-cystathionine and then treated with ox-LDL. The results showed that compared with the controls, ox-LDL stimulation significantly upregulated the expression of THP-1-derived macrophage MCP-1 by enhancing NF-κB p65 phosphorylation, nuclear translocation and DNA binding with the MCP-1 promoter. Compared with the ox-LDL group, 0.3 mmol/L and 1.0 mmol/L L-cystathionine significantly inhibited the expression of THP-1-derived macrophage MCP-1. Mechanistically, 0.3 mmol/L and 1.0 mmol/L L-cystathionine suppressed phosphorylation and nuclear translocation of the NF-κB p65 protein, as well as the DNA binding activity and DNA binding level of NF-κB with the MCP-1 promoter, which resulted in a reduced THP-1-derived macrophage MCP-1 generation. This study suggests that L-cystathionine could inhibit the expression of MCP-1 in THP-1-derived macrophages induced by ox-LDL via inhibition of NF-κB p65 phosphorylation, nuclear translocation, and binding of the MCP-1 promoter sequence after entry into the nucleus.