This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Campos-Toimil, M. Articles by Takeda, K. Search for Related Content PubMed PubMed Citation Articles by Campos-Toimil, M. Articles by Takeda, K. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB CALCIUM COMPOUNDS CALCIUM, ELEMENTAL Related Collections Cell signalling/signal transduction Imaging Receptor pharmacology Endothelium/vascular type/nitric oxide

(Arteriosclerosis, Thrombosis, and Vascular Biology. 2000;20:e34.)
© 2000 American Heart Association, Inc.

Vascular Biology

Inhibition of Type 4 Phosphodiesterase by Rolipram and Ginkgo biloba Extract (EGb 761) Decreases Agonist-Induced Rises in Internal Calcium in Human Endothelial Cells

Manuel Campos-Toimil; Claire Lugnier; Marie-Thérèse Droy-Lefaix; Kenneth Takeda

From Pharmacologie et Physico-chimie des Interactions Cellulaires et Moléculaires (M.C.-T., C.L., K.T.), UMR CNRS 7034, Faculté de Pharmacie, Université Louis Pasteur de Strasbourg, Illkirch, and IPSEN (M.-T.D.-L.), Paris, France. Dr Campos-Toimil is currently at the Department of Pharmacology, University of Cambridge, Cambridge, UK.

Correspondence to Dr K. Takeda, Pharmacologie et Physico-chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Faculté de Pharmacie, BP 24, 67401 Illkirch, France. E-mail kt{at}aspirine.u-strasbg.fr

Abstract—The effects of Gingko biloba extract EGb 761 on 5 isolated, vascular, cyclic nucleotide phosphodiesterase (PDE) isoforms were evaluated. EGb 761 preferentially inhibited PDE4 (IC₅₀=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 ([Ca²⁺]_i) levels in endothelial cells, we examined the effects of EGb 761 on both resting [Ca²⁺]_i levels and agonist-induced rises in [Ca²⁺]_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 µmol/L), and db-cAMP (100 µmol/L) significantly inhibited histamine-, ATP-, and thrombin-induced [Ca²⁺]_i increases in HUVECs without modifying resting [Ca²⁺]_i levels. Similar results were obtained by using a Ca²⁺-free bath solution. EGb 761 (100 mg/L), but not rolipram (50 µmol/L) or db-cAMP (100 µmol/L), also inhibited Ca²⁺ influx into cells having thapsigargin-depleted internal Ca²⁺ stores and bathed in a Ca²⁺-free external solution. Our results are consistent with an inhibition of PDE activity that causes a reduction of agonist-induced increases in [Ca²⁺]_i in HUVECs, mainly by inhibition of Ca²⁺ mobilization from internal stores. It thus may be that the cardiovascular effects of EGb 761 involve inhibition of PDE4 activity and subsequent modification of Ca²⁺ signaling in endothelial cells.

Key Words: Gingko biloba • calcium • phosphodiesterases • rolipram • human umbilical vein endothelial cells