Inhibition of type 4 phosphodiesterase by rolipram and Ginkgo biloba extract (EGb 761) decreases agonist-induced rises in internal calcium in human endothelial cells.
The effects of Gingko biloba extract EGb 761 on 5 isolated, vascular, cyclic nucleotide phosphodiesterase (PDE) isoforms were evaluated. EGb 761 preferentially inhibited PDE4 (IC(50)=25.1 mg/L), the isoform that is mainly present in endothelial cells, in a competitive manner (K:(i)=12.5 mg/L). Because changes in cyclic nucleotide levels may affect intracellular calcium ([Ca(2+)](i)) levels in endothelial cells, we examined the effects of EGb 761 on both resting [Ca(2+)](i) levels and agonist-induced rises in [Ca(2+)](i) in single human umbilical vein endothelial cells (HUVECs) in culture. The effects of EGb 761 were compared with those of rolipram, a selective PDE4 inhibitor that increases cellular cAMP levels, and the cAMP analogue dibutyryl cAMP (db-cAMP). EGb 761 (20 and 100 mg/L), rolipram (50 micromol/L), and db-cAMP (100 micromol/L) significantly inhibited histamine-, ATP-, and thrombin-induced [Ca(2+)](i) increases in HUVECs without modifying resting [Ca(2+)](i) levels. Similar results were obtained by using a Ca(2+)-free bath solution. EGb 761 (100 mg/L), but not rolipram (50 micromol/L) or db-cAMP (100 micromol/L), also inhibited Ca(2+) influx into cells having thapsigargin-depleted internal Ca(2+) stores and bathed in a Ca(2+)-free external solution. Our results are consistent with an inhibition of PDE activity that causes a reduction of agonist-induced increases in [Ca(2+)](i) in HUVECs, mainly by inhibition of Ca(2+) mobilization from internal stores. It thus may be that the cardiovascular effects of EGb 761 involve inhibition of PDE4 activity and subsequent modification of Ca(2+) signaling in endothelial cells.
Campos-Toimil
M
M
Pharmacologie et Physico-chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Faculté de Pharmacie, Université Louis Pasteur de Strasbourg, Illkirch, France.
Lugnier
C
C
Droy-Lefaix
M T
MT
Takeda
K
K
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000975:Antioxidants / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology*; D020441:Ginkgo biloba; D006801:Humans; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010936:Plant Extracts; D020889:Rolipram / Q000494:pharmacology*; D000096983:Ginkgo Extract
D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000975:Antioxidants; D003994:Bucladesine; D002118:Calcium; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D005419:Flavonoids; D010726:Phosphodiesterase Inhibitors; D010936:Plant Extracts; D020889:Rolipram; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract