Search PubMed⌕ Search

Biomedical subjects

M Vigas

Publications and source records attributed to M Vigas.

At least 127 records · Page 7Linked to original sources
PubMed1978

Effect of glucose on the glucagon response to L-dopa in normal and diabetic subjects.

The effect of an oral dose of 1 gm. L-dopa either without or after a concomitant oral administration of 100 gm. glucose on the plasma level of pancreatic glucagon, plasma immunoreactive insulin (IRI), and plasma growth hormone (GH) was assessed in eight normal and 10 insulin-treated diabetic subjects. In the normal group the stimulatory effect o L-dopa on pancreatic glucagon release was reconfirmed. Moreover, in the diabetics essentially the same plasma glucagon increase after drug administration was found, such a response being inhibited in both groups by glucose. The increase of plasma GH after L-dopa in both healthy persons and diabetics and the inhibition of this response by glucose in healthy subjects was reconfirmed. Furthermore, the same effect of exogenous glucose on the L-dopa induced GH release was observed in diabetics. It may be concluded that glucagon may play a pathogenetic role in the worsening of parkinsonian diabetic patients during the treatment with L-dopa and that diabetic hyperglycemia per se seems to be insufficient for an inhibition of the release of both glucagon and GH AFTer L-dopa.

Adult↗
PubMed1978

Effects of phentolamine and clonidine on pituitary-adrenocortical axis during stress in conscious rats.

For evaluation of the effect of several drugs on the hypothalamo-pituitary-adrenocortical axis during stress, after testing various tress stimuli (swimming, restrain) the 15 min exposure of rats to novel environment was chosen. Subcutaneous administration of clonidine hydrochloride (BOEHRINGER; Ingelheim, 60 micorgram kg-1), a drug stimulating alpha-adrenergic receptors, did not result in any any changes in plasma corticosterone level either during basal or under stress conditions. In contrast, the administration of alpha-adrenergic blocking agent--phentolamine (RegitineR CIBA; 4 mg kg-1)--produced a significant elevation of resting corticosterone level, but failed to influence the stress-induced corticosterone increase.

Animals↗
PubMed1978

Serum prolactin after electroconvulsive therapy in man.

When electroconvulsive therapy without anticonvulsive premedication was administered to male psychiatric patients, serum prolactin (PRL) increased regardless to the rather high initial values due to the chlorpromazine treatment. Maximal levels were found 30 min after current application, yet 60 min after electroshock the serum PRL values were declining against pre-shock levels. Infusion of 30 mg of phentolamine during 40 min prior to electroshock was without any effects on the PRL response. The obtained data indicate that even a 5-fold higher initial serum level of PRL fails to inhibit the stress-induced hormone release and that alpha adrenergic receptors scarcely play a role in this response.

Adult↗
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

Effect of insulin and glucose on the activity of insulin-degrading enzymes in rat liver.

The degradation of insulin by insulin protease and glutathion-insulin transhydrogenase (glutathioneproteindisulphide oxidoreductase--EC 1.8.4.2, GIT) was measured in rat liver either after replacing food and water by 15% glucose solution, or after daily insulin administration 8 U daily for 3 days or after fasting. The breakdown of radioiodinated insulin was followed by measuring the increase of TCA soluble radioactivity during incubation of cell fractions with 125I insulin at 37 degrees C. The highest GIT activity was observed in liver microsomes of rats after glucose feeding and after insulin administration, whereas enzyme activity of fasted animals did not essentially differ from corresponding values of normally fed controls. The insulin protease in cytosol of liver cells remained unchanged after these procedures. The important role of GIT in insulin degradation seems to be conclusively demonstrated.

Animals↗
PubMed1977

Inhibition of L-dopa induced growth hormone release in normal and diabetic subjects by glucose administration.

Administration of L-dopa 1 g induced an increase of plasma growth hormone (GH) levels in seven of ten healthy volunteers and in six of ten hyperglycemic insulin-dependent diabetic subjects; the maximal GH response was higher in normal subjects. Addition of 100 g glucose orally to the L-dopa completely abolished the GH response of both groups. The difference between the effect of endogenous hyperglycemia and the effect of a sudden increase of blood sugar after glucose administration on L-dopa induced GH release in diabetic subjects may be explain by the resetting of the hypothalamic control for pituitary GH release to higher levels of blood glucose.

Adult↗
PubMed1976

Alpha-adrenergic regulation of growth hormone release after electroconvulsive therapy in man.

When electroshcok therapy was administered to male psychiatric patients without anticonvulsive premedication, serum growth hormone (GH) increased; the increase was not prevented by an infusion of 20% glucose (5 ml per min) 20 min prior to electroshock. Therefore, the GH rise is not caused by muscle exercise during convulsions. Infusing 30 mg of phentolamine 40 min prior to electroshcok inhibited the GH response. Phentolamine's effect shows that the stress-induced GH release that follows electroconvulsive therapy is mediated by alpha-adrenergic neurons.

Adult↗
PubMed1975

Effect of electroconvulsive therapy without anticonvulsive premedication on serum growth hormone in man.

Serum concentrations of human growth hormone (HGH) were measured in psychiatric patients during the first, third and sixth electroconvulsive therapy (ECT) without anticonvulsive premedication. Serum HGH increased 30 min after the application of current and no differences were found between responses to 1st, 3rd, or 6th ECT. Maximal increase of serum glucose was seen after the first ECT and gradual decreases after the 3rd and 6th ECT were observed

Adolescent↗
PubMed1975

Adrenal hormones and increase of liver tyrosine aminotransferase and tryptophan pyrrolase activity after immobilization in rats.

In adrenomedullectomized rats the postimmobilization increase of liver tyrosine aminotransferase and tryptophan pyrrolase activity was similar as in intact animals, wherease in adrenalectomized rats this response was completely absent. In intact animals a positive correlation between the magnitude of the response of both enzymes and the duration of immobilization and/or the extent of plasma corticosterone increase was observedmit is concluded that the postimmobilization hyperactivity of both enzymes arises exclusively as a consequence of hypercorticosteronaemia, catecholamines and other hormones being without any influence on this response.

Adrenal Glands↗