Phosphodiesterase 3 is present in rabbit and human erythrocytes and its inhibition potentiates iloprost-induced increases in cAMP.
Increases in the second messenger cAMP are associated with receptor-mediated ATP release from erythrocytes. In other signaling pathways, cAMP-specific phosphodiesterases (PDEs) hydrolyze this second messenger and thereby limit its biological actions. Although rabbit and human erythrocytes possess adenylyl cyclase and synthesize cAMP, their PDE activity is poorly characterized. It was reported previously that the prostacyclin analog iloprost stimulated receptor-mediated increases in cAMP in rabbit and human erythrocytes. However, the PDEs that hydrolyze erythrocyte cAMP synthesized in response to iloprost were not identified. PDE3 inhibitors were reported to augment increases in cAMP stimulated by prostacyclin analogs in platelets and pulmonary artery smooth muscle cells. Additionally, PDE3 activity was identified in embryonic avian erythrocytes, but the presence of this PDE in mammalian erythrocytes has not been investigated. Here, using Western blot analysis, we determined that PDE3B is a component of rabbit and human erythrocyte membranes. In addition, we report that the preincubation of rabbit and human erythrocytes with the PDE3 inhibitors milrinone and cilostazol potentiates iloprost-induced increases in cAMP. In addition, cilostamide, the parent compound of cilostazol, potentiated iloprost-induced increases in cAMP in human erythrocytes. These findings demonstrate that PDE3B is present in rabbit and human erythrocytes and are consistent with the hypothesis that PDE3 activity regulates cAMP levels associated with a signaling pathway activated by iloprost in these cells.
Hanson
Madelyn S
MS
Dept. of Pharmacological and Physiological Science, Saint Louis Univ. School of Medicine, M210, 1402 S. Grand Blvd., St. Louis, MO 63104, USA. stumpfms@slu.edu
Stephenson
Alan H
AH
Bowles
Elizabeth A
EA
Sridharan
Meera
M
Adderley
Shaquria
S
Sprague
Randy S
RS
D000328:Adult; D000368:Aged; D000818:Animals; D015153:Blotting, Western; D000077407:Cilostazol; D000242:Cyclic AMP / Q000378:metabolism*; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3 / Q000378:metabolism; D004347:Drug Interactions; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000201:enzymology; D005260:Female; D006801:Humans; D016285:Iloprost / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D020105:Milrinone / Q000494:pharmacology; D058987:Phosphodiesterase 3 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D015363:Quinolones / Q000494:pharmacology; D011817:Rabbits; D013777:Tetrazoles / Q000494:pharmacology; D015854:Up-Regulation
D058987:Phosphodiesterase 3 Inhibitors; D010726:Phosphodiesterase Inhibitors; D015363:Quinolones; D013777:Tetrazoles; C021294:cilostamide; D000242:Cyclic AMP; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D054684:Cyclic Nucleotide Phosphodiesterases, Type 3; C517291:PDE3B protein, human; D016285:Iloprost; D020105:Milrinone; D000077407:Cilostazol