Inactivation of protein kinase C in rat liver during late hypoglycemic phase of sepsis.
Changes in protein kinase C (PKC) (calcium- and phospholipid-dependent protein kinase) activity in rat liver during different metabolic phases of sepsis were studied. Sepsis was induced by cecal ligation and puncture (CLP). Experiments were divided into three groups: control, early sepsis, and late sepsis. Early and late sepsis refers to those animals sacrificed at 9 and 18 h, respectively, after CLP. Hepatic PKC was extracted and partially purified by ammonium sulfate fractionation and DEAE-cellulose chromatography. PKC activity was assayed based on the rate of incorporation of 32p from [gamma-32P]ATP into histone. The results show that during early sepsis, both membrane-associated and cytosolic PKC activities remained relatively unaltered. During late sepsis, membrane-associated PKC was unaffected while cytosolic PKC activity was decreased by 19.5-34.4%. Kinetic analysis of the data on cytosolic PKC during late phase of sepsis reveals that the Vmax values for ATP, histone, Ca2+, phosphatidylserine, and diacylglycerol were decreased by 23.4, 22.1, 19.5, 25, and 34.4%, respectively, with no changes in their Km values. These data indicate that cytosolic PKC activity was inactivated in rat liver during late hypoglycemic phase of sepsis. Since PKC-mediated phosphorylation plays an important role in regulating hepatic glucose metabolism, an inactivation of cytosolic PKC may contribute to the development of hypoglycemia during late phase of sepsis.
Hsu
C
C
Department of Physiology, Graduate Institute of Medicine, Kaohsiung Medical College, Taiwan.
Jao
H C
HC
Yang
S L
SL
Hsu
H K
HK
Liu
M S
MS
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D007003:Hypoglycemia / Q000201:enzymology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D015636:Magnesium Chloride / Q000494:pharmacology; D008297:Male; D011493:Protein Kinase C / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000201:enzymology*
D015636:Magnesium Chloride; D011493:Protein Kinase C