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The discovery that nitric oxide (NO) profoundly affects vascular tone (and other physiologic functions) was recognized with a Nobel Prize. Subsequently, carbon monoxide (CO), another gas, was found to influence vascular tone. Now, a U.S. and Canadian team demonstrates that yet another gas, hydrogen sulfide (H2S), also plays a role.
The team deleted the gene for cystathionine γ-lyase (CSE) in mice; this enzyme generates H2S and is found primarily in the endothelium. As predicted, levels of H2S in the serum, heart, aorta, and other tissues were very low in the mutant mice, which had marked hypertension and low endothelium-dependent vasorelaxation. IV sodium hydrosulfide (an H2S donor molecule) produced transient blood pressure lowering. H2S pr…