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

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 (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.

Protection against β-amyloid induced abnormal synaptic function and cell death by Ginkgolide J

“…Recent studies have revealed that the Ginkgo biloba extract, EGb-761, exerts PDE4 inhibitory activity with a pharmacological profile similar to that of rolipram [6,41]. The possibility that Ginkgo biloba extracts might also rescue LTP inhibition by Aβ 1-42 oligomers prompted us to test them on hippocampal slices.…”

“…Though the literature suggests that the PDE4 inhibitory activity in Ginkgo extracts is associated with the flavanoids [6,21], we assayed both P8A and each of the ginkgolides for their ability to inhibit PDE4. There was a trace of activity in P8A and none in any of the individual ginkgolides (data not shown) suggesting that the effects studied here are independent of PDE4.…”

Anti-TNF-α Properties of New 9-Benzyladenine Derivatives with Selective Phosphodiesterase-4- Inhibiting Properties

“…Cytosolic PDE isoforms (PDE1, PDE3, PDE4, and PDE5) were purified by anion-exchange chromatography from the medial layer of bovine aorta and cytosolic PDE2 was isolated from cultured bovine aortic endothelial as previously described (25). PDE activities were measured by radio enzymatic assay at a substrate concentration of 1 M cAMP in the presence of 15000 cpm […”

Effects of Gingko biloba extract (EGb 761) on vascular smooth muscle cell calcification induced by β-glycerophosphate

“…It not only reduced the deposition of calcium, but also inhibited osteogenic transdifferentiation, which are consistent with experimental animal studies and with clinical studies linking EGb 761 to beneficial effects on VC. 14,19,[29][30][31] However, the detailed mechanism by which EGb 761 may influence this process is unclear. More research is required to observe the EGb 761 in patients with renal failure and to confirm a possible protective effect of EGb 761 against VC.…”

“…[14][15][16] Moreover, several studies have been reported the antioxidant, repressing atherosclerosis, and anti-apoptotic properties of EGb 761 and its constituents. 15,[17][18][19][20] Additionally, it can stabilize the changes in mitochondrial membrane potential occurred due to excessive ROS and peroxynitrite generation and help prevent the disruption of ionic homeostasis. [21][22][23] However, the pharmacological potential and mechanism of action of EGb 761 in VC of ESRD is yet to be explored.…”