Article date: May 1994
By: Robin Plevin, Nicola A. Kellock, Michael J.O. Wakelam, Roger Wadsworth, in Volume 112, Issue 1, pages 311-315
The aim of the study was to characterize the effects of hypoxia on agonist‐stimulated phospholipase D (PLD) and phospholipase C activity of sheep pulmonary artery cultured smooth muscle cells.
Endothelin‐1 (ET‐1), 5‐hydroxytryptamine (5‐HT) and the protein kinase C (PKC) activator tetradecanoylphorbol acetate (TPA), stimulated a time‐ and concentration‐dependent increase in [3H]‐phosphatidylbutanol accumulation. This was abolished by pretreatment of the cells with the PKC inhibitor, Ro‐318220, suggesting that agonist‐stimulated phospholipase D activity is dependent upon the activation of PKC.
Hypoxia (Po2 20 mmHg for 30 min) stimulated basal [3H]‐phosphatidylbutanol accumulation by approximately 2 fold and this activity was abolished by preincubation of the cells with 10 μm Ro‐318220.
In cells preincubated in low O2 containing medium for 30 min, the subsequent agonist‐stimulated accumulation of [3H]‐phosphatidylbutanol was reduced. However, the decrease in stimulation was greater for ET‐1 and 5‐HT than for TPA.
ET‐1 and TPA stimulated a time‐dependent increase in protein kinase C‐ mediated psuedosubstrate phosphorylation. Following preincubation for 30 min in low O2 containing media, basal pseudosubstrate phosphorylation increased whilst the fold stimulation by TPA and ET‐1 decreased.
In cells preincubated in low O2 containing medium, ET‐1‐stimulated [3H]‐inositol phosphate accumulation was reduced by approximately 30– 40%. This reduction was reversed by preincubation of the cells with Ro‐318220.
These results suggest a role for PKC in the effects of hypoxia on PLD in pulmonary artery smooth muscle cells.
The aim of the study was to characterize the effects of hypoxia on agonist‐stimulated phospholipase D (PLD) and phospholipase C activity of sheep pulmonary artery cultured smooth muscle cells.
Endothelin‐1 (ET‐1), 5‐hydroxytryptamine (5‐HT) and the protein kinase C (PKC) activator tetradecanoylphorbol acetate (TPA), stimulated a time‐ and concentration‐dependent increase in [3H]‐phosphatidylbutanol accumulation. This was abolished by pretreatment of the cells with the PKC inhibitor, Ro‐318220, suggesting that agonist‐stimulated phospholipase D activity is dependent upon the activation of PKC.
Hypoxia (Po2 20 mmHg for 30 min) stimulated basal [3H]‐phosphatidylbutanol accumulation by approximately 2 fold and this activity was abolished by preincubation of the cells with 10 μm Ro‐318220.
In cells preincubated in low O2 containing medium for 30 min, the subsequent agonist‐stimulated accumulation of [3H]‐phosphatidylbutanol was reduced. However, the decrease in stimulation was greater for ET‐1 and 5‐HT than for TPA.
ET‐1 and TPA stimulated a time‐dependent increase in protein kinase C‐ mediated psuedosubstrate phosphorylation. Following preincubation for 30 min in low O2 containing media, basal pseudosubstrate phosphorylation increased whilst the fold stimulation by TPA and ET‐1 decreased.
In cells preincubated in low O2 containing medium, ET‐1‐stimulated [3H]‐inositol phosphate accumulation was reduced by approximately 30– 40%. This reduction was reversed by preincubation of the cells with Ro‐318220.
These results suggest a role for PKC in the effects of hypoxia on PLD in pulmonary artery smooth muscle cells.
DOI: 10.1111/j.1476-5381.1994.tb13070.x
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