The effect of the long-term inhibition of hydrogen sulfide production on the reactivity of the cardiovascular system in Wistar rats

In this study, we investigated the blood pressure responses of the peripheral bed in vivo after chronic hydrogen sulfide (H₂S) inhibition combined with acute nitric oxide (NO) deficiency. We also evaluated the role of endogenously produced H₂S in the vasoactive responses of large- and medium-sized arteries in vitro. Changes in integrated blood pressure responses were measured after chronic inhibition of cystathionine-γ-lyase, an enzyme involved in H₂S synthesis, with DL-propargylglycine (PPG), and acute inhibition of NO-synthase with nonspecific L-N^G-nitro arginine methyl ester (L-NAME), and vasoactive responses of the thoracic aorta (TA) and mesenteric artery (MA) were investigated after acute incubation with PPG. We confirmed that chronic H₂S deficiency had no effect on blood pressure, heart trophycity, noradrenaline, and H₂S donor vasoactive responses but induced renal hypertrophy and a decrease in acetylcholine-induced hypotensive and L-NAME-induced hypertensive responses. Acute H₂S deficiency led to an increase in basal tone (MA) or active tone (TA), whereas endothelium-dependent vasorelaxation remained unaffected. Long-term administration of PPG revealed a role of endogenous H₂S in the bioavailability of endothelial NO in peripheral arteries. When both H₂S and NO were lacking, the activation of H₂S-independent compensatory mechanisms plays an important role in maintaining the vasodilator responses of the cardiovascular system.