Extracellular 2,3-cyclic adenosine monophosphate is a potent inhibitor of preglomerular vascular smooth muscle cell and mesangial cell growth [corrected].
Recently we discovered that intact kidneys release into the extracellular compartment 2',3'-cAMP (a positional isomer of 3',5'-cAMP with unknown pharmacology) and metabolize 2',3'-cAMP to 2'-AMP, 3'-AMP, and adenosine. Because adenosine inhibits growth of vascular smooth muscle cells and mesangial cells, we tested the hypothesis that extracellular 2',3'-cAMP attenuates growth of preglomerular vascular smooth muscle and mesangial cells via production of adenosine. For comparison, all of the experiments were performed with both 2',3'-cAMP and 3',5'-cAMP. In study 1, 2',3'-cAMP, 3',5'-cAMP, 5'-AMP, 3'-AMP, or 2'-AMP was incubated with cells and purines measured in the medium by mass spectrometry. Both preglomerular vascular smooth muscle and mesangial cells metabolized 3',5'-cAMP to 5'-AMP and adenosine; 5'-AMP to adenosine; 2',3'-cAMP to 2'-AMP, 3'-AMP, and adenosine; and 2'-AMP and 3'-AMP to adenosine. 3-Isobutyl-1-methylxanthine (phosphodiesterase inhibitor) and 1,3-dipropyl-8-p-sulfophenylxanthine (ecto-phosphodiesterase inhibitor) blocked conversion of 3',5'-cAMP to 5'-AMP and adenosine, and alpha,beta-methylene-adenosine-5'-diphosphate (CD73 inhibitor) blocked conversion of 5'-AMP to adenosine. These enzyme inhibitors had little effect on metabolism of 2',3'-cAMP, 2'-AMP, or 3'-AMP. For study 2, 2',3'-cAMP and 3',5'-cAMP profoundly inhibited proliferation (thymidine incorporation and cell number) of both cell types, with 2',3'-cAMP more potent than 3',5'-cAMP. Antagonism of A(2B) receptors (MRS-1724), but not A(1) (1,3-dipropyl-8-cyclopentylxanthine), A(2A) (SCH-58261), or A(3) (VUF-5574) receptors, attenuated the growth inhibitory effects of 2',3'-cAMP and 3',5'-cAMP. Extracellular 2',3'-cAMP inhibits growth of preglomerular vascular smooth muscle and mesangial cells more profoundly than does 3',5'-cAMP. Although both cAMPs inhibit growth in part via conversion to adenosine followed by A(2B) receptor activation, their metabolism is mediated by different enzymes.
Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, 100 Technology Dr, Suite 450, Pittsburgh, PA 15219, USA. edj@pitt.edu
Edwin K
EK
Jackson
Jin
J
Ren
Delbert G
DG
Gillespie
Raghvendra K
RK
Dubey
D000227:Adenine Nucleotides / Q000494:pharmacology*; D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D002853:Chromatography, Liquid; D045604:Extracellular Fluid; D008297:Male; D050527:Mesangial Cells / Q000166:cytology* / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000254:growth & development* / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D043704:Receptor, Adenosine A2B / Q000378:metabolism
D000227:Adenine Nucleotides; D043704:Receptor, Adenosine A2B; C010565:2',3'-cyclic AMP