The interaction between reactive NO and heme iron or other interactants provide molecular sources for many biochemical processes and functional effects in mammals. One example includes the activation of guanylyl cyclase by the nitrosyl-heme prosthetic group, resulting in vasodilation. Notably, nitroglycerin yields NO, which results in vasodilation. DNICs, generated within cells, may also act as nitrosating intermediates with involvement in vascular signaling. In combination with superoxide, NO forms peroxynitrite, which may serve as an oxidizing substrate. Other effectors of vascular function include nitrite and nitrate, which affect vasodilation, platelet function, and angiogenesis. Low-molecular-weight S-nitrosothiols, via NO+, also provide a source for protein modifications that promote effects such as vasodilation and platelet inhibition. RSH, sulfhydryl species.