Template:Aquatic layer topics. An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 m. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth âs surface.
Murad discovered in 1977 that nitroglycerin and related artery-widening compounds act by releasing nitric oxide. Furchgott later concluded that cells in the inner lining of blood vessels secrete some unknown substance that makes vessels dilate.
Nitric oxide (NO â¢) synthesized in endothelial cells, from the terminal guanidino nitrogen atom of L-ARG, by means of NO-synthase (NOS), activates guanylyl-cyclase in smooth muscle cells and plateletes, increasing the levels of the intracellular messenger cyclic guanylyl phosphate (GMPc).