Pyruvate kinase in cultured rat hepatocytes

1981 ◽  
Vol 9 (5) ◽  
pp. 399-399
Author(s):  
GRAEME P. POOLE ◽  
ANTHONY D. POSTLE ◽  
DAVID P. BLOXHAM
Keyword(s):  
Pyruvate Kinase ◽  
Rat Hepatocytes ◽  
Cultured Rat Hepatocytes

scholarly journals The turnover of L-type pyruvate kinase in cultured rat hepatocytes

1982 ◽  
Vol 204 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Graeme P. Poole ◽  
David P. Bloxham
Keyword(s):  
Pyruvate Kinase ◽  
Rat Hepatocytes ◽  
Cell Protein ◽  
Rapid Phase ◽  
First Order Kinetics ◽  
Enzyme Degradation ◽  
Fructose 1,6 Bisphosphatase ◽  
Cultured Rat Hepatocytes ◽  
In Cells

Hepatocytes were isolated by collagenase perfusion of livers from rats that had been allowed access to a carbohydrate-rich diet or laboratory chow or had been deprived of food 48h before use. By incubation with l-[4,5-3H]leucine and precipitation with anti-(L-type pyruvate kinase) sera the rates of synthesis and degradation of L-type pyruvate kinase were measured in freshly prepared cells and hepatocytes maintained in monolayer culture for up to 5 days. Hepatocytes from carbohydrate-rich-diet-fed rats synthesized more L-type pyruvate kinase than did cells from chow-fed animals, which in turn synthesized more than cells from 48h-starved rats. Hepatocytes maintained in culture for up to 5 days synthesized L-type pyruvate kinase at similar rates to freshly prepared cells. The degradation of [3H]leucine-labelled L-type pyruvate kinase was shown to be biphasic. A phase with t½ (half-time) 4.9h and a duration of 8–10h was followed by a phase with t½ 79.2h. Cells from chow-fed and carbohydrate-rich-diet-fed rats showed similar patterns of degradation of L-type pyruvate kinase. The addition of 2mm-fructose and 0.1μm-insulin to the culture medium increased the t½ of the rapid phase to 12h in cells isolated from carbohydrate-rich-diet-fed rats, but not in cells from chow-fed rats. The secondary, slower, phase of degradation remained unaffected. The degradation of fructose 1,6-bisphosphatase and total cell protein followed first-order kinetics. The half-life of fructose 1,6-bisphosphatase was 41.0h in cells from chow-fed animals and 48.5h in cells from carbohydrate-rich-diet-fed donors. Fructose and insulin did not affect the rate of enzyme degradation. We propose that there is a role for protein catabolism in the short-term and long-term control of L-type pyruvate kinase concentration.

scholarly journals Insulin regulation of pyruvate kinase activity in cultured rat hepatocytes, in the presence of vasopressin, ionophore A23187 or 4β-phorbol 12β-myristate 13α-acetate

1988 ◽  
Vol 252 (3) ◽  
pp. 717-721 ◽  
Author(s):  
R A Pittner ◽  
J N Fain
Keyword(s):  
Cyclic Amp ◽  
Pyruvate Kinase ◽  
Kinase Activity ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Ionophore A23187 ◽  
Short Term ◽  
Pyruvate Kinase Activity ◽  
Cultured Rat Hepatocytes ◽  
Early Inhibition

The short-term interactions of insulin and vasopressin on pyruvate kinase (PK) activity were studied in primary cultures of rat hepatocytes. (1) Vasopressin inhibited PK activity by approx. 30% within 15 s, but activity returned to control values by 5 min. The transient inhibition by vasopressin was mimicked by either 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) or ionophore A23187. (2) Insulin alone transiently inhibited PK activity at 1 min, but stimulated PK activity at 5 and 15 min. (3) Insulin completely antagonized the early inhibition by vasopressin, PMA or A23187 of PK activity at 15 s. (4) Insulin inhibited PK activity in the presence of vasopressin, PMA or A23187 at 5 min. (5) 8-Bromo cyclic AMP inhibited PK activity within 15 s, and this inhibition was maintained for at least 5 min. Insulin did not antagonized the inhibition by the cyclic AMP analogue. These results show that insulin under appropriate conditions can act as an inhibitor or activator of PK.

Nutrition and somatomedin. XXVI. Molecular regulation of IGF-I by insulin in cultured rat hepatocytes

Diabetes ◽  
1991 ◽  
Vol 40 (11) ◽  
pp. 1525-1530 ◽  
Author(s):  
L. S. Phillips ◽  
S. Goldstein ◽  
C. I. Pao
Keyword(s):  
Rat Hepatocytes ◽  
Molecular Regulation ◽  
Igf I ◽  
Cultured Rat Hepatocytes

Vanadate induction of L-type pyruvate kinase mRNA in adult rat hepatocytes in primary culture

Diabetes ◽  
1991 ◽  
Vol 40 (4) ◽  
pp. 462-464 ◽  
Author(s):  
M. Miralpeix ◽  
J. F. Decaux ◽  
A. Kahn ◽  
R. Bartrons
Keyword(s):  
Primary Culture ◽  
Pyruvate Kinase ◽  
Rat Hepatocytes ◽  
Adult Rat ◽  
Adult Rat Hepatocytes
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