Vasorelaxation with Garlic? It’s a Gas

Abstract

Garlic is reputed to have various beneficial effects on health, and its consumption has been correlated with a decrease in several risk factors for cardiovascular disease. Noting that garlic is rich in organosulfur compounds and that hydrogen sulfide (H 2 S), like nitric oxide and carbon monoxide, may act as a gaseous signaling molecule in the cardiovascular system (see Lefer), Benavides et al. investigated the possibility that polysulfide compounds in garlic might provide a source of vascular H 2 S. Using a polarographic H 2 S sensor, they showed that addition of garlic juice to human red blood cells (RBCs) elicited H 2 S production. Glucose, which enabled the maintenance of the pool of reduced RBC glutathione, promoted sustained production of H 2 S in the presence of garlic; moreover, glutathione plus garlic produced H 2 S even in the absence of RBCs. Experiments with membrane-permeant and -impermeant thiol-blocking reagents indicated that H 2 S production involved exofacial RBC membrane thiols, as well as intracellular thiols. H 2 S produced in the presence of either garlic or garlic-derived polysulfides elicited relaxation of precontracted rat aortic rings, an effect that did not require a functional endothelium. Thus, the authors propose that garlic produces beneficial vasoactive effects by promoting the production of H 2 S. G. A. Benavides, G. L. Squadrito, R. W. Mills, H. D. Patel, T. S. Isbell, R. P. Patel, V. M. Darley-Usmar, J. E. Doeller, D. W. Kraus, Hydrogen sulfide mediates the vasoactivity of garlic. Proc. Natl. Acad. Sci. U.S.A. 104 , 17977-17982 (2007). [Abstract] [Full Text] D. J. Lefer, A new gaseous signaling molecule emerges: Cardioprotective role of hydrogen sulfide. Proc. Natl. Acad. Sci. U.S.A. 104 , 17907-17908 (2007). [Full Text]