scholarly journals Comparison of the effects of [leucine]enkephalin and angiotensin on hepatic carbohydrate and cyclic nucleotide metabolism

1988 ◽  
Vol 249 (3) ◽  
pp. 669-676 ◽  
Author(s):  
S K Hothi ◽  
R P Leach ◽  
M A Titheradge
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Pyruvate Kinase ◽  
Cyclic Nucleotide ◽  
Plasma Membranes ◽  
Kinase Activity ◽  
Nucleotide Metabolism ◽  
Pyruvate Kinase Activity ◽  
Leucine Enkephalin ◽  
Glucose Synthesis

The effects of [leucine]enkephalin and angiotensin on hepatic carbohydrate and cyclic nucleotide metabolism are compared. Both peptides stimulated glycogenolysis as a result of an increase in phosphorylase a activity and enhanced glucose synthesis from [2-14C]pyruvate, although neither had any significant effect on pyruvate kinase activity. Although the magnitudes of the effects of both peptides on glycogenolysis were comparable and unaffected by the presence of insulin. [Leu]enkephalin proved to be more efficacious in enhancing gluconeogenesis, the response being comparable with that to glucagon. Both effectors decreased the intracellular concentration of cyclic AMP in hepatocytes when incubated under control conditions and after addition of sub-optimal concentrations of glucagon. This was correlated with the ability of the two peptides to inhibit both basal and hormone-stimulated adenylate cyclase activity in purified liver plasma membranes.

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.

Red blood cell age, pyruvate kinase activity, and insulin receptors. Evidence that monocytes and RBCs may behave differently

Diabetes ◽  
1983 ◽  
Vol 32 (11) ◽  
pp. 1017-1022 ◽  
Author(s):  
A. Camagna ◽  
R. De Pirro ◽  
L. Tardella ◽  
L. Rossetti ◽  
R. Lauro ◽  
...  
Keyword(s):  
Blood Cell ◽  
Pyruvate Kinase ◽  
Red Blood Cell ◽  
Kinase Activity ◽  
Insulin Receptors ◽  
Pyruvate Kinase Activity ◽  
Cell Age

Red Blood Cell Age, Pyruvate Kinase Activity, and Insulin Receptors: Evidence that Monocytes and RBCs May Behave Differently

Diabetes ◽  
1983 ◽  
Vol 32 (11) ◽  
pp. 1017-1022 ◽  
Author(s):  
A. Camagna ◽  
R. D. Pirro ◽  
L. Tardella ◽  
L. Rossetti ◽  
R. Lauro ◽  
...  
Keyword(s):  
Blood Cell ◽  
Pyruvate Kinase ◽  
Red Blood Cell ◽  
Kinase Activity ◽  
Insulin Receptors ◽  
Pyruvate Kinase Activity ◽  
Cell Age

Pyruvate kinase activity in cerebral hemispheres and cerebellum-brainstem of normal and hypoxic-ischemic newborn rats

2004 ◽  
Vol 3 (3) ◽  
pp. 152-155 ◽  
Author(s):  
Hacer Yapicioglu ◽  
Mehmet Satar ◽  
Nejat Narli ◽  
Levent Kayrin ◽  
Ercan Tutak
Keyword(s):  
Pyruvate Kinase ◽  
Kinase Activity ◽  
Cerebral Hemispheres ◽  
Newborn Rats ◽  
Pyruvate Kinase Activity

Superoxide dismutase and cytochrome oxidase in collapsed lungs: possible role in reexpansion edema

1988 ◽  
Vol 65 (1) ◽  
pp. 235-241 ◽  
Author(s):  
R. M. Jackson ◽  
A. L. Brannen ◽  
C. F. Veal ◽  
J. D. Fulmer
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome Oxidase ◽  
Pyruvate Kinase ◽  
Kinase Activity ◽  
H2o2 Production ◽  
Lung Collapse ◽  
Pyruvate Kinase Activity ◽  
Sod Activity ◽  
Control Rabbit ◽  
Radical Production

This study examined the effects of lung collapse, a condition that causes relative hypoxia in lung tissues, on superoxide dismutase (SOD), cytochrome oxidase (cyt ox), and pyruvate kinase (py ki) activities in rabbits. Cyanide-insensitive respiration measurements were done in collapsed and contralateral lungs, as an index of intracellular free radical production. Rabbits' right lungs were collapsed for 7 days after which the animals were killed. We found that control rabbit lungs contained approximately 25 SOD units/mg DNA measured with 10(-5) M KCN (total SOD) and approximately 11 SOD units/mg DNA measured with 10(-3) M KCN (mitochondrial or MnSOD). Right lung collapse caused a 25% decrease in mitochondrial SOD activity after 7 days (P less than 0.05), whereas no significant changes occurred in right or left lungs' total SOD activity. In control rabbits cyt ox activity averaged approximately 0.009 mumol ferrocytochrome c.min-1.mg DNA-1. Right lung collapse caused a greater than 40% decrease in cyt ox activity after 7 days of collapse (P less than 0.05), whereas cyt ox activity in contralateral left lungs did not change. Pyruvate kinase activity, a marker for anaerobic glycolysis resulting from tissue hypoxia, increased 49% in collapsed right lungs (P less than 0.01). Cyanide-insensitive respiration was 83% higher in 7 day-collapsed lungs (2.28 +/- 0.66 microliters O2.min-1.g-1) compared with contralateral lungs (1.24 +/- 0.34, P less than 0.05), indicating increased O2-. and H2O2 production in this tissue after homogenization at normoxic PO2 (approximately 150 Torr).(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document