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Biomedical subjects

S Németh

Publications and source records attributed to S Németh.

At least 37 records · Page 2Linked to original sources
PubMed1983

Inhibitory effect of fasting on the activation of liver glycogen phosphorylase of rats by arginine-vasopressin.

The i.v. bolus of 50 ng kg-1 Arginine-vasopressin administered to adult male rats anaesthetized with Pentobarbital (50 mg kg-1 i.p.) increases the activity of liver glycogen phosphorylase in fed and 24 h fasted rats to the same extent; after 25 ng kg-1 of the drug the enzyme response after fasting is barely detectable, whereas in the fed animals a response similar to that after 50 ng kg-1 persists.

Animals↗
PubMed1982

The role played by hormonal factors in the rapid activation of liver glycogen phosphorylase in traumatized rats.

In adult male SPF rats anaesthetized with pentobarbital and subjected to traumatization in revolving Noble-Collip drums for 2 min (= 120 revolutions) maximal increases of liver glycogen phosphorylase activity were observed. In experiments on rats with permanent arterial catheters for blood sampling no posttraumatic increase of plasma norepinephrine and an only slight increase of plasma epinephrine was observed if the animals were traumatized under anaesthesia, in contrast to the considerable increases in the plasma level of both hormones in rats subjected to the injury without anaesthesia. Time and extent of the phosphorylase response of anaesthetized rats after trauma were compared with changes in enzyme activity after i.v. administration of exogenous epinephrine or glucagon. A nearly maximal response after 1 microgram kg-1 epinephrine was present within 1 min, whereas after 0.1 micrograms kg-1 of glucagon there was comparable phosphorylase activation 2 min after administration of the hormone. The plasma renin-angiotensin activity was not increased after injury for 2 min under anaesthesia so that only the increase in plasma vasopressin fitted in with the criteria for possible activators of phosphorylase. An additional role of glucagon also cannot be excluded on the basis of data obtained by the present authors. The increase of phosphorylase activity in this type of stress is ensured by several mechanisms. Moreover, the high effectivity of these hormonal factors in evoking the phosphorylase response even without major activation of the sympathicoadrenal system is underlined.

Anesthesia↗
PubMed1981

Inhibition of stress induced hyperglucagonemia by administration of glucose in normal and alloxan-diabetic rat.

The increase in plasma pancreatic glucagon which is known to occur under several stress conditions was confirmed in fed and 18 h prefasted rats subjected to a low, "stress producing" dose of the Noble-collip drum procedure (400 revolutions per 400 s). A single dose of exogenous glucose ( 1 g kg-1) injected 3 min and 20 s before stress into the jugular vein of intact fasted or fed animals anesthetized with pentobarbital 930 mg kg-1) completely abolished their hyperglucagonemic response in stress. In alloxan-diabetic hyperglycemic rats the stress-hyperglucagonemia was exaggerated, but was also suppressible by exogenous glucose. It was concluded that: 1. the stress induced hyperglucagonemic response of both intact and alloxan-diabetic rats was completely suppressible by administration of i.v. bolus of exogenous glucose; 2. the site inhibiting effect of glucose might be located either at the level of A cell or at the level of "'glucoreceptors" in hypothalamus.

Animals↗
PubMed1979

The stress induced increase of liver phosphorylase A and cyclic AMP in adrenomedullectomized and adrenalectomized rats.

In adult male rats injected with Pentobarbital, 50 mg.kg-1 i.p. and subjected immediately after administration of the anaesthetic to 400 revolutions (lasting of 6 min and 40 s) in rotating Noble-Collip drums the activity of the active form of hepatic phosphorylase was increased at time 0 after injury without respect to previous adrenomedullectomy or adrenalectomy (7 weeks or 10 days before, respectively). Completeness of surgery was checked by plasma catecholamines which were essentially near zero. The level of liver cAMP was increased in intact and adrenomedullectomized animals at time zero. 90 min after injury a recovery of enzyme activity towards basal levels was observed in contrast to cAMP which was increased in all the three groups. A net glycogenolytic response was found in the injured animals irrespective of previous surgery. It is concluded that for the stress induced activation of hepatic phosphorylase the presence of adrenal cortical and medullary tissue is not always indispensable.

Adrenal Medulla↗
PubMed1978

The effect of stress or glucose feeding on hepatic tyrosine aminotransferase activity and liver and plasma tyrosine level of intact and adrenalectomized rats.

The increase of hepatic tyrosine aminotransferase and the fall of plasma tyrosine in rats subjected to immobilization is reconfirmed. Moreover, the same effects three hrs after exposuing the animals to 400 revolutions in Noble-Collip drums are described. However, in bilaterally adrenalectomized rats both hepatic tyrosine aminotransferase and plasma tyrosine remain unchanged after injury and the liver tyrosine level increase. Finally, in animals fed overnight exclusively with 15% glucose solution the well-known decrease of hepatic tyrosine aminotransferase was found paralleled by increased plasma tyrosine levels. A regulatory role of tyrosine aminotransferase in establishing the level of tyrosine in plasma is suggested.

Adrenalectomy↗
PubMed1978

A three hours study of the response of plasma corticosterone and of three liver enzymes in rats subjected to stress in the late afternoon or during the morning hours.

In adult male rats kept under controlled illumination (lights on from 6 a.m.--6 p.m.) the existence of higher afternoon values of plasma corticosterone ("B") is reconfirmed. Moreover, plasma "B" increases induced by 400 revolutions in Noble-Collip drums or immobilization for 2.5 h were found substantially less pronounced if stressor application took place at 4 p.m. rather than 8 a.m. so that essentially no difference between morning and afternoon poststress peaks was observed. Also the response to 0.05 mg ACTH i.p. was smaller in the afternoon experiments. Additionally three liver enzymes the activity of which is increased by corticosterone released under conditions of stress were also studied. Higher afternoon activity of liver tyrosine aminotransferase (TAT) and tryptophan pyrrolase (TP) was observed in spite of fasting from 8 a.m. imposed to the animals taking part in the afternoon experiments. The activity of phosphoenolpyruvate carboxykinase (PEPCK) was also increased in the afternoon probably because of the food deprivation. Immobilization-induced increase in the activity of all three enzymes showed a similar blunting as plasma "B" response, so that no differences between morning and afternoon were found in peak poststress values. In conclusion, the low plasma "B" response of rats at a time when the animals begin the active part of their day seems to have important metabolic implications.

Adrenocorticotropic Hormone↗
PubMed1977

Alpha-adrenergic control of growth hormone release during surgical stress in man.

The mechanisms involved in the initial release of growth hormone (GH) during cholecystectomy have been studied after the administration of phentolamine in saline and in isotonic glucose, and after the administration of 10% glucose. Infusion of these substances was started 10 min before and terminated 30 min after skin incision. The serum GH levels 30 min after skin incision in a nontreated control group were raised to 14.4 +/- 1.0 ng/ml. The alpha-adrenergic blockade by phentolamine (20 mg during 40 min) regardless of whether administered in saline or in isotonic glucose inhibited GH response to surgery (4.3 +/- 2.1 ng/ml, or 2.2 +/- 0.4 ng/ml). The administration of 10% glucose (40 g during 40 min) led to a diminished response in some, but not in all the patients (6.2 +/- 1.2 ng/ml). It is concluded that the alpha-adrenergic mechanism participates in GH response to surgery.

Adolescent↗
PubMed1977

The effect of repeated immobilization on the level of plasma corticosterone and on the activity of several liver enzymes in rats.

The effect of repeated stress on the level of plasma corticosterone and on the activity of several target enzymes for this hormone in the liver was studied. In adult male rats immobilized for 2.5 hrs daily, on day 7 the response of both plasma corticosterone and hepatic tyrosine aminotransferase is modified: After similar increases immediately after immobilization as in aminals stressed for the first time, in the conditioned rats precocious decreases to initial values take place. Moreover, on day 4, 24 hrs after a third immobilization, there are increases arise partly at least as a consequence of diminished food intake, as shown by comparing them with data from pair-fed rats. Partial fasting leading also to slight increase of hepatic glucose-6-phosphatase activity constitutes an important part of repeated stress with substantial impacts on metabolic processes.

Adrenalectomy↗
PubMed1977

Lack of effect of acid-base alterations on growth hormone secretion in man.

In order to study the possible effect of acid-base alterations on growth hormone (GH) secretion in man the exercise-induced GH secretion was compared with the tentative GH release resulting from the acidosis due to hyperlactacidemia after the infusion of fructose. Submaximal exercise on bicycle ergometer resulted in a significant increase of plasma GH and lactate and in acid-base alterations. The infusion of 60 g of fructose during 60 min was without effect on plasma GH level in spite of the increase of serum lactate and slight acid-base alterations. It is concluded that no causal relationship may be found between the acid-base alterations and the increase of plasma GH during physical exercise.

Adult↗
PubMed1977

The effect of stress on the activity of hepatic tryptophan pyrrolase, of tyrosine aminotransferase in various organs and on the level of tryptophan in the liver and plasma of rats.

In rats subjected to 400 revolutions in Noble-Collip drums, hepatic tryptophan pyrrolase activity increases and plasma tryptophan level decreases. After bilateral adrenalectomy, the alterations of plasma tryptophan are even more pronounced and liver tryptophan increases in contrast to tryptophan pyrrolase activity which remains unchanged after injury. The possible significance of the posttraumatic increase of tryptophan pyrrolase in intact animals for brain serotonin metabolism and hepatic gluconeogenesis is underlined. The activity of tyrosine aminotransferase in liver, brain, adrenal, kidney and muscle tissue of rats was determined with special reference to the possible effect of the before-mentioned stress procedure. Organ homogenates were centrifuged at 15000 x g and both supernatants and pellets were investigated for enzyme activity with the exception of the liver, where only the supernatant fraction was used. Tyrosine aminotransferase activity in the liver supernatant considerably exceeded the corresponding values in both supernatant and pellet of the remaining organs, in which a prevalence of the mitochondrial enzyme was obvious. In contrast to the clear-cut increase of the hepatic enzyme during stress, essentially no changes were noted in the brain, the adrenals, kidney or muscle under similar conditions...

Adrenal Glands↗