Increased cyclic AMP in aortas of cholesterol fed rabbits.

Cyclic Amp (cAMP) levels were measured in the aortas of rabbits fed a cholesterol rich diet for either 24 days (Group I), 86 days (Group II) or 86 days followed by 54 days of a normal diet (Group III). Aortic levels of cholesterol and cholesterol esters, calcium and collagen and noncollagen protein synthetic rates were also measured at each time period. Cyclic AMP levels were unchanged in the Group I animals but were significantly elevated in Groups II & III. Aortic levels of cholesterol and cholesterol esters, calcium and collagen and noncollagen protein synthetic rates were also significantly elevated in Groups II & III but unchanged in Group I. Since cAMP levels were not changed in Group I animals the increase in cAMP appears to be a later, adaptive change in response to the feeding of a cholesterol rich diet. The observation that cAMP levels are increased in response to cholesterol feeding is important since cAMP is known to be involved with a wide range of metabolic functions, which may have a significant effect on the development of vascular disease.