AJP - Heart and Circulatory Physiology, Vol 232, Issue 2 191-H196, Copyright © 1977 by American Physiological Society
Cyclic nucleotide metabolism and vasodilation in canine mesenteric artery
D. Mailman, W. Pawilk, A. P. Shepherd, L. L. Tague and E. D. Jacobson
The uptake and extracellular and intracellular metabolism of
radioisotopically labeled cyclic 3',5'-adenosine monophosphate (cAMP) and
dibutyryl cAMP (DBcAMP) was determined in canine mesenteric arteries
incubated in vitro. Intracellular tissue uptake was measured by
radioisotope counting and labeled metabolites separated by thin-layer
chromatography. Extracellularly, cAMP was extensively metabolized to AMP,
adenosine, and Pi. DBcAMP was metabolized to monobutyryl cAMP (MBcAMP)
intracellularly. Vasodilation of the mesenteric circulation in vivo was
produced by cAMP, its metabolites and DBcAMP. DBcAMP caused greater
vasodilation than cAMP but had a response time to its peak effect of 12 min
versus 90 s for cAMP. The vasodilator properties of cAMP and DBcAMP were
related to their metabolism. It was concluded that the vasodilation caused
by cAMP was due to cAMP metabolites produced by extracellular metabolism.
