Protein kinase a activity is increased in rat heart during late hypodynamic phase of sepsis.
Changes in the activities of protein kinase A (PKA, or cAMP-dependent protein kinase) in rat heart during different cardiodynamic phases of sepsis were investigated. Sepsis was induced by cecal ligation and puncture. Experiments were divided into three groups: control, early sepsis, and late sepsis. Early and late sepsis refers to those animals killed at 9 and 18 h, respectively, after cecal ligation and puncture. Cardiac PKA was extracted and partially purified by acid precipitation, ammonium sulfate fractionation, and 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 based on the rate of incorporation of [gamma-32P]ATP into histone. Results obtained show that during early sepsis, both type I and type II PKA activities were unaffected. During late sepsis, type I PKA activities were stimulated by 66.7-97.7%, while type II PKA activities remained constant. Kinetic analysis of the data on type I PKA during late sepsis reveals that the Vmax values for ATP, cAMP, and histone were increased by 84.7, 66.7, and 97.7%, respectively; while the Km values for ATP, cAMP, and histone were unaltered. These data indicate that type I PKA is activated in rat heart during late hypodynamic phase of sepsis. Since kinase-mediated phosphorylation plays an important role in regulating myocardial function and metabolism, an activation of type I PKA during late sepsis may contribute to the development of altered myocardial function during hypodynamic phase of sepsis.
Yang
S L
SL
Department of Physiology, Graduate Institute of Medicine, Kaohsiung Medical College, Taiwan.
Hsu
C
C
Lue
S I
SI
Hsu
H K
HK
Liu
M S
MS
D000818:Animals; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D018476:Hypokinesia / Q000201:enzymology* / Q000209:etiology; D008274:Magnesium / Q000502:physiology; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000150:complications / Q000201:enzymology*
D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D008274:Magnesium