Synthesis of platelet-activating factor and its receptor expression in Kupffer cells in rat carbon tetrachloride-induced cirrhosis.
OBJECTIVE
To determine the platelet-activating factor (PAF) synthesis and its receptor expression in Kupffer cells in rat carbon tetrachloride-induced cirrhosis.


METHODS
Kupffer cells, isolated from the livers of control and CCl4-induced cirrhotic rats, were placed in serum-free medium overnight. PAF saturation binding, ET-1 saturation and competition binding were assayed. ET-1 induced PAF synthesis, mRNA expression of PAF, preproendothelin-1, endothelin A (ETA) and endothelin B (ETB) receptors were also determined.


RESULTS
A two-fold increase of PAF synthesis (1.42 +/- 0.14 vs 0.66 +/- 0.04 pg/microg DNA) and a 1.48-fold increase of membrane-bound PAF (1.02 +/- 0.06 vs 0.69 +/- 0.07 pg/microg DNA) were observed in activated Kupffer cells of cirrhotic rats. The application of ET-1 to Kupffer cells induced PAF synthesis in a concentration-dependent manner in both cirrhotic and normal rats via ETB receptor, but PAF synthesis in the activated Kupffer cells was more effective than that in the normal Kupffer cells. In activated Kupffer cells, PAF receptor expression and PAF binding capacity were markedly enhanced. Activated Kupffer cells raised the [125 I]-ET-1 binding capacity, but changed neither the affinity of the receptors, nor the expression of ETA receptor.


CONCLUSIONS
Kupffer cells in the course of CCl4-induced cirrhosis are the main source of increased PAF. ET-1 is involved endogenously in stimulating the PAF synthesis in activated Kupffer cells via ETB receptor by paracrine. ETA receptor did not appear in activated Kupffer cells, which may exacerbate the hepatic and extrahepatic complications of cirrhosis.
Lu
Yin-Ying
YY
Department of Gastroenterology, 302 Hospital of Chinese PLA, 100 Xisihuan Middle Road, Beijing 100039, China.
Wang
Chun-Ping
CP
Zhou
Lin
L
Chen
Yan
Y
Su
Shu-Hui
SH
Feng
Yong-Yi
YY
Yang
Yong-Ping
YP
D000818:Animals; D002251:Carbon Tetrachloride / Q000633:toxicity; D004195:Disease Models, Animal; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism; D007728:Kupffer Cells / Q000473:pathology / Q000502:physiology*; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D010972:Platelet Activating Factor / Q000235:genetics* / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A / Q000235:genetics* / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000235:genetics* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism
D019332:Endothelin-1; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D012333:RNA, Messenger; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D002251:Carbon Tetrachloride