Effect of cyclosporin A on endothelin synthesis by cultured human renal cortical epithelial cells.
We report here for the first time that human renal proximal tubular cells secrete endothelin, clear evidence of de-novo endothelin synthesis by these cells and the effect of cyclosporin A (CsA) on endothelin synthesis both in short-term (24 h) and medium-term (5-day) culture. Human renal cortical epithelial cells were cultured and shown to possess proximal tubular characteristics. These cells produced endothelin in culture in a time-dependent manner, as measured by radioimmunoassay (291.6 +/- 51.4 pg/well/24 h). Furthermore, endothelin production by these cells was significantly decreased by up to 80% by cycloheximide (1051.8 +/- 54.9 pg/mg cell protein/24 h versus 253.2 +/- 12.6 pg/mg cell protein/24 h), showing that these cells actively synthesize endothelin. In short-term culture (24 h), CsA significantly inhibited endothelin synthesis at a medium concentration of 10,000 micrograms/l. No change in endothelin synthesis was seen at lower CsA concentrations. In contrast, over a 5-day period, a non-significant increase in endothelin synthesis was observed at CsA concentrations of 2000 micrograms/l (152.5 +/- 20.4%); however, cell growth was significantly decreased at this concentration (71.33 +/- 6.39%). Using a newly developed two-site immunoradiometric assay specific for endothelin-1 (ET-1), we demonstrate that ET-1 is the major endothelin isoform produced by human renal proximal tubular cells.
Ong
A C
AC
Department of Medicine, UCL Medical School, Rayne Institute, UK.
Jowett
T P
TP
Scoble
J E
JE
O'Shea
J A
JA
Varghese
Z
Z
Moorhead
J F
JF
D000818:Animals; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D016232:Endothelins / Q000096:biosynthesis*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007672:Kidney Cortex / Q000187:drug effects* / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D017207:Rats, Sprague-Dawley
D016232:Endothelins; D016572:Cyclosporine