Transport and distribution of (45)Ca(2+) in the perfused rat liver and the influence of adjuvant-induced arthritis.
The purpose of the present work was to investigate Ca(2+) transport and distribution under the conditions of the intact rat liver in health and disease (adjuvant-induced arthritis). The multiple-indicator dilution technique was used with the simultaneous injection of (45)Ca(2+) and indicators into the portal vein under defined conditions and analysis of the outflow profiles by means of a space-distributed variable transit time model. The best description of the (45)Ca(2+) outflow profiles corresponds to a model that assumes rapid distribution of (45)Ca(2+) between the vascular space and the cell surface and a slower transfer into the hepatocytes. In kinetic terms two distinct cellular pools were distinguishable, the cytosol and the endoplasmic reticulum. The concentration of Ca(2+) in the cytosol was much lower than in the vascular space and in the endoplasmic reticulum. The most prominent modification observed in the livers of arthritic rats was the increased Ca(2+) concentration in the hormone-sensitive cellular pool. Furthermore, reduced rates of Ca(2+) influx and efflux between the hormone-sensitive cellular pool and the cytosolic space were also detected in combination with a significantly reduced expression of the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA2) protein. All these observations mean that in livers from arthritic rats more time is required to replenish the hormone sensitive Ca(2+) stores.
Department of Biochemistry, University of Maringá, Maringá, Brazil.
Karina Sayuri
KS
Utsunomiya
Luiz Guilherme
LG
Scaliante
Adelar
A
Bracht
Emy Luiza
EL
Ishii-Iwamoto
D000818:Animals; D001169:Arthritis, Experimental / Q000378:metabolism*; D001692:Biological Transport; D002132:Calcium Radioisotopes / Q000737:chemistry / Q000378:metabolism*; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D051381:Rats; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism
C506948:Atp2a2 protein, rat; D002132:Calcium Radioisotopes; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases