ALTERED EXPRESSION OF CYCLIC-NUCLEOTIDE PHOSPHODIESTERASE ISOZYMES DURING CULTURE OF AORTIC ENDOTHELIAL-CELLS

Primary cultures of bovine aortic endothelial cells (BAEC) express cyc lic nucleotide phosphodiesterase (CN PDE) isozymes of the PDE2, PDE4 a nd PDES gene families. We report here that the isozyme profiles of CN PDE and the amounts of each vary with the passage number of BAEC cultu res. Characterization by anion-exchange chromatography and pharmacolog ical criteria were used to study CN PDE in early (4-6), intermediate ( 6-10), and late (>17) passages of purified BAEC. PDE2 and a minor frac tion of PDES accounted for cyclic GMP hydrolysis in early passages, bu t both isozymes were lost with cell passage. Cyclic AMP was hydrolyzed by both PDE2 and PDE4 isozymes in early passage endothelial cells, bu t PDE4 was increased dramatically in higher passage cells. Also appear ing in the higher passage cells were prominent PDE1 and minor PDE3 act ivities. The ratios of cytosolic to particulate activities were simila r at all passages. BAEC PDE isoforms in intact cells assessed by [H-3] -adenine prelabeling showed that atriopeptin II decreased isoprotereno l-induced cyclic AMP accumulation in early but not later passage cells , consistent with the loss of PDE2 expression. Enhancement of isoprote renol-induced cyclic AMP accumulation by rolipram, a PDE4 inhibitor, w as also greatly diminished during culture passages. Changes in CN PDE isoform expression and consequent cyclic AMP turnover validate the imp ortance of considering cell passage number when cultures of BAEC are u sed to study the regulation of endothelial cell cyclic nucleotide meta bolism and processes mediated by cyclic nucleotides in this model syst em. (C) 1997 Elsevier Science Inc.