Liver protein kinase A activity is decreased during the late hypoglycemic phase of sepsis.
Changes in protein kinase A (PKA, or cAMP-dependent protein kinase) activity in the rat liver during different metabolic phases of sepsis were investigated. Sepsis was induced by cecal ligation and puncture (CLP). Experiments were divided into 3 groups: control, early sepsis, and late sepsis. Early and late sepsis refer to those animals killed at 9 and 18 h, respectively, after CLP. Hepatic PKA was extracted and partially purified by acid precipitation, ammonium sulfate fractionation, and diethylaminoethyl (DEAE)-cellulose chromatography. PKA was eluted from DEAE-cellulose column with a linear NaCl gradient. Two peaks of PKA, type I (eluted at low ionic strength) and type II (eluted at high ionic strength), were collected and their activities were determined on the basis of the rate of incorporation of [gamma-32-P]ATP into histone. The results show that during early sepsis, both type I and type II PKA activities remained unchanged. During late sepsis, type I PKA activity was decreased by 40.7-53.6%, whereas type II PKA activity was unaffected. Kinetic analysis of the data on type I PKA during the late phase of sepsis reveals that the Vmax (maximal velocity) values for ATP, cAMP, and histone were decreased by 40.7, 53.6, and 47.3%, respectively whereas the Km (substrate concentration required for half-maximal enzymatic activity) values for ATP, cAMP, and histone were unaltered. These data indicate that type I PKA was inactivated during the late hypoglycemic phase of sepsis in the rat liver. Because PKA-mediated phosphorylation plays an important role in the regulation of hepatic glucose metabolism, an inactivation of PKA may contribute to the development of hypoglycemia during the late phase of sepsis.
Hsu
C
C
Department of Physiology, Graduate Institute of Medicine, Kaohsiung Medical College, Taiwan.
Hsu
H K
HK
Yang
S L
SL
Jao
H C
HC
Liu
M S
MS
D000818:Animals; D002118:Calcium / Q000378:metabolism; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D018450:Disease Progression; D005947:Glucose / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D007003:Hypoglycemia / Q000209:etiology / Q000378:metabolism*; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000150:complications / Q000378:metabolism*
D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D005947:Glucose; D002118:Calcium