M. Diazmunoz et al., MODIFICATIONS OF INTRACELLULAR CALCIUM-RELEASE CHANNELS AND CALCIUM MOBILIZATION FOLLOWING 70-PERCENT HEPATECTOMY, Archives of biochemistry and biophysics, 349(1), 1998, pp. 105-112
The aim of this study was to investigate the properties of ryanodine a
nd IP3 receptors in regenerating liver following 70% hepatectomy, and
to evaluate the hepatic Ca2+ distribution and mobilization during this
process, Specific [H-3]ryanodine and [H-3]Ips binding to hepatic smoo
th endoplasmic reticulum membranes, as well as subcellular Ca2+ determ
ination by atomic absorption flame photometry and Ca2+ mobilization by
INDO-1 AM spectrofluorescence in hepatocytes, was performed in regene
rating livers after surgical 70% hepatectomy. Incorporation of C-14 am
ino acids into proteins and of P-32 into phospholipids was done in sub
cellular fractions, Ryanodine receptor K-d presented a dramatic increa
se after 12 h of surgery and remained high up to 2 days of treatment,
IP3 receptor B-max showed a significant augmentation starting at 6 h a
fter hepatectomy and returning to normal values after 1 week, Cytosoli
c total calcium content decreased from 12 h until 4 days after hepatec
tomy whereas the microsomal and mitochondrial total calcium increased
at 1 and 2-4 days of liver regeneration, which coincided with the diff
erential turnover of proteins and phospholipids in these fractions, AT
P-induced Ca2+ transients in hepatocytes of 24-h-hepatectomized rats c
onfirmed the altered sensitivity of the ryanodine receptor toward its
ligand, since 10 times more ryanodine was necessary to alter the ATP-i
nduced Ca2+ transient, The data support the notion that the calcium re
lease channels are targets of mechanisms of metabolic control during t
he proliferative response following 70% hepatectomy and might be part
of the modified intracellular Ca2+ dynamics during liver regeneration,
(C) 1998 Academic Press.