Calcium transport by rat liver plasma membranes during sepsis.
The effects of sepsis on the ATP-dependent Ca2+ transport in rat liver plasma membranes were investigated. Sepsis was induced by cecal ligation and puncture (CLP). Control rats were sham-operated. The results show that the ATP-dependent Ca2+ transport by liver plasma membranes was not affected during early sepsis (9 hr after CLP) but was decreased by 30-50% (P < 0.05) during late sepsis (18 hr after CLP). Kinetic analysis of the data indicates that during late sepsis, the Vmax values for ATP and for Ca2+ were decreased by 38.5% (P < 0.05) and 41.8% (P < 0.05), respectively, while the Km values for ATP and Ca2+ remained unchanged. Mg2+ stimulated ATP-dependent Ca2+ transport. The Mg(2+)-stimulated activity was unaffected during early sepsis but was decreased by 34-63% (P < 0.05) during late sepsis. These data demonstrate that ATP-dependent Ca2+ transport in rat liver plasma membranes was impaired during late sepsis and that the impairment is associated with a mechanism not affecting the affinity of the Ca2+ transporter for ATP and Ca2+. Since plasma membrane ATP-dependent Ca2+ transport plays an important role in the regulation of intracellular Ca2+ homeostasis in hepatocytes, an impairment in the ATP-dependent Ca2+ transport by liver plasma membranes during late sepsis may have a pathophysiological significance in contributing to the development of altered hepatic metabolism during septic shock.
Lau
Y T
YT
Department of Surgery and Physiology, Chang Gung Medical College, Taiwan, Republic of China.
Hwang
T L
TL
Chen
M F
MF
Liu
M S
MS
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004837:Epinephrine; D005934:Glucagon; D008099:Liver / Q000378:metabolism; D008297:Male; D009638:Norepinephrine; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000378:metabolism*; D012772:Shock, Septic / Q000503:physiopathology*
D000255:Adenosine Triphosphate; D005934:Glucagon; D002118:Calcium; D009638:Norepinephrine; D004837:Epinephrine