Effect of muscular exercise and glycogen depletion on rat liver and kidney phosphoenolpyruvate carboxykinase

Sánchez-Medina, F; Sanchez-Urrutia, L.; Medina, José M.; Mayor, Federico

doi:10.1016/0014-5793(71)80495-7

Cited by 19 publications

(6 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the acidosis produced by this system is not as pronounced as that found after swimming (where blood lactate reaches 10 mM in 15 min [S]) the magnitude of renal PEPCK activity and gluconeogenic capacity increases was similar to that found after 2 h swimming [6,7]. These findings suggest that kidney cortex PEPCK is very sensitive to acidosis.…”

Section: Resultssupporting

confidence: 55%

Stimulation of rat renal phosphoenolpyruvate carboxykinase activity after an intravenous lactic acid load

et al. 1981

Self Cite

View full text Add to dashboard Cite

Section: Resultssupporting

confidence: 55%

Stimulation of rat renal phosphoenolpyruvate carboxykinase activity after an intravenous lactic acid load

et al. 1981

Self Cite

View full text Add to dashboard Cite

“…Phosphoenolpyruvate carboxykinase activity was measured spectrophotometrically in the direction of oxaloacetate synthesis in the presence of an excess of malate dehydrogenase at 30°C, as described previously (Sanchez-Medina et al, 1971). Protein was determined by the method of Lowry et al (1951), with bovine serum albumin as standard.…”

Section: Methodsmentioning

confidence: 99%

Stimulation of phosphoenolpyruvate carboxykinase (guanosine triphosphate) activity by low concentrations of circulating glucose in perfused rat liver

Moreno¹,

Sanchez-Urrutia²,

Medina³

et al. 1975

Biochemical Journal

View full text Add to dashboard Cite

(Received I1 Febrmary 1975) 1. After nicotinic acid treatment, rat liver glycogen is depleted and phosphoenolpyruvate carboxykinase activity increased, to about twice the initial value. 2. The increase in phosphoenolpyruvate carboxykinase activity promoted by nicotinic acid is prevented by cycloheximide or actinomycin D, suggest-ing that this effect is produced by synthesis of the enzyme de novo. 3. Despite the enhancement of phosphoenolpyruvate carboxykinase activity and glycogen depletion, which occurs 5h after the injection of nicotinic acid, the gluconeogenic capacity of liver is low and considerably less than the values found in rats starved for 48h. 4. When the livers of well-fed rats are perfused in the presence of low concentrations of glucose, the activity of phosphoenotpyruvate carboxykinase significantly incteases compared with the control. 5. This increase is not related to the glycogen content, but seemns to be also the result of synthesis of the enzyme de novo, since this effect is coumteracted by previous treatment with cycloheximide or actinomycin D. 6. Phosphoenolpyruvate carboxykinase activity is not increased in the presence of low concentrations of circulating glucose when 40mnM-imidaiole (an activator of phosphodiesterase) is added to the perfusion medium. 7. Addition of dibutyryl cyclic AMP to the perfusion medium reguftsg in an incrtease in phosphoenolpyruvate carboxykinase activity, in spite of the presenCe of normal concentrations of circulating glucose. On the other hand, the concentration of cyclic AMP in the liver increases when that of glucose in the medium is low. 8.These results suggest that, in the absence of hormonal factors, the regulation of phosphoenolpyruvate carboxykinase can be accomplished by glucose itself, inadequate concentrations of it resulting in the induction of the enzyme. The mediator in this regulation, as in hormonal regulation, seems to be cyclic AMP.

show abstract

“…Phosphoenol pyruvate carboxykinase (GTP: oxaloacetate carboxy-lyase, EC 41 132) activity was measured in liver homogenates using a modification of the method of Sanchez-Medina et al [16]. The animals were fasted for 24 h prior to sacrifice and the liver was removed under pentobarbitone anaesthesia.…”

Section: Gluconeogenic Enzymes and Substratesmentioning

confidence: 99%

Mechanism of oestrogen and progesterone effects on lipid and carbohydrate metabolism: alteration in the insulin: glucagon molar ratio and hepatic enzyme activity

Mandour

Kissebah

Wynn

1977

Eur J Clin Investigation

112

View full text Add to dashboard Cite

As in women receiving oestrogens the administration of 17beta-oestradiol to ovariectomized female rats caused a rise in fasting plasma triglycerides and a fall in plasma glucose. Progesterone, on the other hand, had no significant effects. In the oestradiol treated rats, the portal vein basal insulin levels were slightly reduced. Oestradiol, however, had a marked suppressive effect on the alpha cells of the pancreas resulting in a greater reduction in basal glucagon and impaired glucagon response to alanine infusions. The relative insulin to glucagon (I/G) molar concentration ratio in portal vein blood was increased. Oestradiol also produced a dose dependent increase in the activity of the liver lipogenic enzymes, acetyl CoA carboxylase and fatty acid synthetase. On the other hand, the activity of the gluconeogenic rate limiting enzyme phosphoenol-pyruvate carboxykinase (PEPCK) was inhibited. The cross-over pattern of gluconeogenic intermediates confirmed inhibition of gluconeogenesis at this step, an effect which is similar to that induced by relative insulin 'excess'. Progesterone produced an increase in the portal vein insulin concentrations. Both the basal and the alanine-stimulated glucagon levels were also increased. The I/G molar ratio in portal vein blood of progesterone treated rats remained unaltered and the hepatic lipogenic and gluconeogenic enzyme activities were similar to control animals. These data suggest that insulin activity is increased relative to glucagon in the liver of oestradiol-treated rats due to the rise in portal vein I/G ratio. The changes in liver lipogenic and gluconeogenic enzymes and the alterations in fasting plasma triglycerides and glucose in response to oestrogens could be secondary to this effect.

show abstract

Effect of muscular exercise and glycogen depletion on rat liver and kidney phosphoenolpyruvate carboxykinase

Cited by 19 publications

References 16 publications

Stimulation of rat renal phosphoenolpyruvate carboxykinase activity after an intravenous lactic acid load

Stimulation of rat renal phosphoenolpyruvate carboxykinase activity after an intravenous lactic acid load

Stimulation of phosphoenolpyruvate carboxykinase (guanosine triphosphate) activity by low concentrations of circulating glucose in perfused rat liver

Mechanism of oestrogen and progesterone effects on lipid and carbohydrate metabolism: alteration in the insulin: glucagon molar ratio and hepatic enzyme activity

Contact Info

Product

Resources

About