title: Ultraviolet radiation-induced decreases in tension and phosphorylase a formation in rat aorta.
abstract: Helical strips of rat aorta contracted with norepinephrine (10 nM) respond to ultraviolet (UV) radiation (340-360 nm) with a transient decrease in tension. The UV radiation-dependent relaxation is completely reversible and endothelial cell-independent. Although decreased tension is associated with a rise in tissue cGMP content, the cAMP level is unchanged after UV radiation. A significant inhibition of phosphorylase a formation which occurs coincidently with the rise in cGMP and decline in tension is observed with UV radiation. The effects of UV radiation on cGMP, phosphorylase a formation and tension were blocked by methylene blue. Relaxation and inhibition of phosphorylase a formation in response to UV radiation were also partially reversed with higher concentrations of norepinephrine (100 nM). Our results suggest that cGMP may mediate UV radiation-dependent reactions by reducing cytoplasmic Ca2+.
mesh_terms: D000818:Animals; D001011:Aorta / Q000201:enzymology / Q000502:physiology / Q000528:radiation effects*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000528:radiation effects*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology / Q000502:physiology / Q000528:radiation effects*; D009638:Norepinephrine / Q000494:pharmacology; D010762:Phosphorylase a / Q000096:biosynthesis*; D006005:Phosphorylases / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D014466:Ultraviolet Rays
chemical_list: D010762:Phosphorylase a; D006005:Phosphorylases; D009638:Norepinephrine