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Biomedical subjects

E Bergamini

Publications and source records attributed to E Bergamini.

17 recordsLinked to original sources
PubMed1992

Effects of the administration of thyroid hormone on the plasma levels of atrial natriuretic peptides and on atrial myoendocrine cells in the rat: an immunochemical, ultrastructural, and stereological study.

The effects of an altered thyroidal status on the levels of immunoreactive (ir-) atrial natriuretic peptide (ANP) in serum and in the right and left atria, as well as on the subcellular structures of atrial myoendocrine cells were explored in groups of male Sprague Dawley rats given the vehicle or triiodothyronine in the toxicological dose-range (50 micrograms/100 g bw/day) for 0,5, 1,2,4,7 or 14 days. Plasma levels of ir-ANP were 30% higher in T3-treated rats compared with controls at 0,5 and 1 day after hormone administration and then decreased to levels 30-40% lower than controls at days 2 and 4 to rise again above control values on day 7 and 14. Atrial ir-ANP levels decreased at first both in the right and in the left atria with different latencies (1 and 2 days, respectively) and rose back towards control levels by day 4. Changes in the numerical density of specific granules followed a parallel temporal pattern. An increased in the individual volume of the granules followed was also observed. Investigation into the circulatory effects of T3 administration showed that the heart rate was increased by hour 12 after hormone administration (simultaneously with the early rise in plasma ir-ANP levels) and that blood pressure was increased by day 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

[Effects of catecholamine treatment on UDPG levels in white and red skeletal muscle].

Adrenaline causes of 5 fold increase of glucose-6-phosphate and of glucose-1-phosphate both in the white extensor digitorum longus and in the red soleus (where the levels of the two sugar phosphates are significantly lower). On the other hand, UDPG levels--which are similar in the two muscles--are significantly decreased after adrenaline. It has been concluded that the levels of glucose-1-phosphate and of UDPG in muscle are not bound to change together.

Animals↗
PubMed1979

[Modifications in glycogen following white and red muscle denervation in rats].

Native glycogen was prepared from intact and 12 and 36 h denervated white and red rat muscles, ultracentrifuged on a sucrose density gradient (3) and the fractions stained by the iodine method (4). An increase of the optical density of the fractions showing a relatively high density was observed, which may be related to the well known changes of muscle glycogen levels after denervation.

Animals↗
PubMed1979

Influence of age on the sensitivity of the rat to streptozotocin.

The relationship between age and sensitivity to the diabetogenic effect of streptozotocin was investigated. Changes in the serum levels of several parameters (glucose, immunoreactive insulin, lipids), as well as changes of the pancreatic insulin content were monitored at 2, 4, 8, 24 and 48 h after the intravenous administration of different doses of streptozotocin in rats of various weights. Different concentrations of blood glucose and lipid and different amounts of pancreatic immunoreactive insulin could be found in rats of different ages 24 and 48 h after injection of the same dose of the drug (in mg/kg body weight). Also, age-dependent changes of serum immunoreactive insulin could be observed as early as 4 h after streptozotocin administration. All these changes indicate that the sensitivity of the rat to the diabetogenic effect of streptozotocin is inversely related to the age of the animals. Most likely, age-dependent pancreatic factors have an important role. In fact, the changes of the minimum dose of streptozotocin required to cause diabetes in rats of different weights closely parallel the age-related changes of the total immunoreactive insulin content of the pancreas of the intact rats. The role of other age-related factors which may influence the effectiveness of streptozotocin action is briefly discussed.

Aging↗
PubMed1979

Developmental changes of glycogen enzymes in fast and slow muscles of the rat.

Glycogen synthase (GS), Branching enzyme (BE), Glycogen Phosphorylase (GPho) and the Debranching enzyme (DE) activities were studied in the white extensor digitorum longus (ELD) and in the red soleus (S) muscles of rats during the developmental period from birth to the young adulthood. During the first days of postnatal life all enzyme activities similarly increase in both ELD and in S. BE and DE seem to rise faster and reach the adult levels earlier than GS and GPho. Significant differences can be seen between ELD and S by age 14--21 days: glycogenolytic enzymes rise higher in the ELD, GS activity is similar in both muscles whereas BE activity is higher in S. All these develop changes are completed in 25 days. Thereafter, only GPho activity in the ELD continues to slowly increase.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1975

Different mechanisms in testosterone action on glycogen metabolism in rat perineal and skeletal muscles.

Testosterone affects glycogen levels in perineal and skeletal muscles by two distinct mechanisms. Both of them show similar sensitivity to androgens (0.1 mg/rat/day of testosterone being effective) and to antiandrogen administration. However, they differ because of the pattern of glycogen increase (early after the androgen injection in the perineal muscles; slowly and with a linear function of time in the skeletal muscles), and because of the different sensitivities to adrenolectomy, diabetes and hypophysectomy. Also, the biochemical changes induced by testosterone in muscles differ. The rate of sugar uptake and phosphorylation is increased in the perineal muscle only; the rate of glucose incorporation into glycogen is increased in the perineal but depressed in the skeletal muscles. Therefore, in the former case glycogen accumulation depends mainly on increased synthesis; in the latter, it is probably the result of a glycogen sparing effect.

Adrenalectomy↗
PubMed1975

Age-dependent changes in the sensitivity of the rat to a diabetogenic agent (streptozotocin).

Changes of plasma glucose levels have been investigated in rats of 50, 70, 90, 110 and 150 g BW after the intravenous injection of 0, 40, 60, 80 or 100 mg/kg BW of streptozotocin. The effect of streptozotocin was dependent on the dose used and on the size of the animals. With all animal sizes studied, a transient acute hyperglycemic response to streptozotocin was observed at doses lower than those required to produce persistent hyperglycemia. Smaller animals required higher doses of streptozotocin in order to produce changes comparable to those observed in larger animals.

Aging↗
PubMed1975

[Biochemical aspects of hormone-dependent muscles].

Different sensitivity of muscle fibres to hormones might be an important factor in regulating differing properties of individual muscles, in addition to the well known neural effects on muscle fibres. The peculiar sensitivity of rat perineal muscles to androgens is a striking example, whose relevance to function is self explanatory in muscles connected with the sexual apparatus. Besides these qualitative differences, quantitative differences too can be observed when the responses of different muscles to hormones active on glycogen are compared. Data concerning the effects of androgens, insulin and hydrocortisone on perineal and skeletal muscles (soleus, gastrocnemius, extensor digitorum longus, quadricipes, obliquus externus abdominis and diaphragm) support this statement. However, the physiological meanings of these differences remain obscure.

Animals↗