It could be just L-arginine. This amino acid is the substrate from which nitric oxide (NO) is made. Nitric oxide itself is a small molecule gas which diffuses easily and rapidly - that's why it's used as a signalling molecule, so anything which claims to help its absorption is either bullshit or inserts itself into your cell membranes to act as a transporter, which is also bullshit. If you're interested in amplifying the effect of NO, well, that's what viagra is for.
I think omar tan you're possibly referring to nitrous oxide, which is another pharmacologically active gas - aka laughing gas or entonox. Which is fun, but be careful as too much can cause symptoms such as death.