Fig. 5.

H₂S production in MTHFR++ carriers and healthy volunteers. (A) l-Cys caused a significant increase of H₂S production in platelets harvested from healthy volunteers or MTHFR++ carriers compared with respective vehicle (°°°P < 0.001 and ^§§§P < 0.001). Both PAG (10 mM) and AOAA (1 mM) significantly inhibited the increase in H₂S production induced by l-Cys in healthy volunteers (^###P < 0.001 and ^##P < 0.01) and in MTHFR++ carriers (⁺P < 0.05 and ⁺⁺⁺P < 0.001). MTHFR++ carriers produced a higher level of H₂S compared with healthy volunteers both in basal (vehicle) or in stimulated (l-Cys) condition (**P < 0.01). Results are expressed as nmol/mg proteins per minute and calculated as mean ± SEM from six MTHFR++ carriers and nine healthy volunteers. Data were analyzed using one-way ANOVA followed by Bonferroni post-test. (B) H₂S plasma level was higher in MTHFR++ carriers compared with healthy volunteers (**P < 0.01). Results are expressed as µM and calculated as mean ± SEM from four samples. Data were analyzed using Student t test.