Translocation of protein kinase C is associated with inhibition of 5-HT uptake by cultured endothelial cells.
Acute exposure (30 min-1 h) of bovine pulmonary artery endothelial cells in culture (BPAEC) to phorbol myristate acetate (PMA 10(-10)-10(-6) M) resulted in concentration-dependent decrement in serotonin (5-HT) uptake. Neither cell viability (trypan blue exclusion or release of deoxyglucose) nor activity of another plasma membrane function, angiotensin-converting enzyme activity, were affected. A decrease in 5-HT uptake was also noted with phorbol 12,13 dibutyrate and mezerein, but not with 4-alpha-phorbol 12,13 didecanoate, which does not stimulate protein kinase C (PKC). Inhibition of 5-HT uptake by PMA (160 nM) was reversed in a concentration-dependent manner by pretreatment of cells with the PKC inhibitor staurosporine (3-100 nM). BPAEC were treated with PMA (160 nM) for 1 h, and activities of PKC in cytosolic and membrane compartments were determined. PMA did not significantly affect total cellular PKC activity but resulted in a translocation of activity from cytosol to membrane (control membrane activity 67 +/- 4%; PMA-treated membrane activity 97 +/- 1% of total cellular PKC). Thus we propose that translocation of PKC from cytosol to membrane results in inhibition of 5-HT uptake by BPAEC.
Myers
C L
CL
Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Lazo
J S
JS
Pitt
B R
BR
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005473:Fluoxetine / Q000494:pharmacology; D007099:Imipramine / Q000494:pharmacology; D007700:Kinetics; D009550:Nigericin / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011651:Pulmonary Artery; D012701:Serotonin / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D005473:Fluoxetine; D012701:Serotonin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D007099:Imipramine; D009550:Nigericin