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Biomedical subjects

M Cernohorský

Publications and source records attributed to M Cernohorský.

18 recordsLinked to original sources
PubMed1993

[3H-dihydroalprenolol binding to beta-adrenergic receptors in adipocyte membrane fractions of rats premedicated with estrogens].

Oestradiol administration in vivo has been shown to potentiate the adrenergic lipolysis in vitro in rat epididymal adipose tissue; one of the possible explanations of this oestradiol effect might be the direct influencing of beta-adrenergic receptors. In order to show this possible mechanism of action, in direct radioligand binding studies we have estimated the specific binding parameters of beta-adrenergic receptors in controls and in vivo pretreated rats by a single dose of oestrogen (200 microgram.kg-1 s.c. 24 hours prior sacrification of rats). Beta-adrenergic receptor binding studies we performed with membrane fraction of homogenates of epididymal adipose cells, the radioligand used was L-[3H]-dihydroalprenolol (3H-DHA). No clear-cut differences in the saturation curves of 3H-DHA were found between control and pretreated oestradiol rats; the density of beta-adrenoreceptors (Bmax) was practically identical (269 v. 270 fmol.mg-1 protein) and also differences in dissociation constants (Kd) of both groups were minimal (1.05 vs. 0.95 nmol.1-1). Minimal differences between control and oestradiol pretreated rats were also found in displacement studies, where the effects of 1-isomers of norepinephrine and epinephrine was tested. Thus, it seems possible that the potentiating effect of in vivo pretreatment by oestradiol on adrenergic lipolysis of epididymal adipose tissue in vitro is not caused by the direct influencing of beta-adrenergic receptors. The explanation of this effect will be necessary to search on other steps of the adrenergic reaction which lead to lipolysis or in influencing other receptors (e.g. alpha-adrenergic receptors).

Adipose Tissue↗
PubMed1977

Effect of different albumin media on the lipid-mobilizing action of sympathicotropic substances in vitro.

The authors studied the effect of adrenotropic substances on lipolysis in rat epididymal adipose tissue in albumin medium in vitro. On using albumins of different origin (human, bovine), the pD2 values for catecholamines differed by more than one order, in correlation to the type of albumin used. The isopropylnorsynephrine pD2 values did not differ. The addition of ascorbic acid (100 microng/ml) raised the catecholamine pD2 values and completely equalized the pD2 values found in both media. The pD2 values for the synephrine derivative did not alter. The propranolol pA2 values were not negatively affected by the addition of ascorbic acid. Ascorbic acid also produced a mild increase in the maximum lipid-mobilizing values obtained with any of the given substances in either medium. It was concluded in the discussion that catecholamines are oxidized at different rates in different albumin media and that this oxidation can be inhibited by adding ascorbic acid. Ascorbic acid likewise mildly stimulates the maximum lipid-mobilizing effect. The authors recommend the addition of ascorbic acid to albumin medium as a regular component for the study of adrenergic lipid mobilization.

Albumins↗
PubMed1975

7-oxa-13-prostynoic acid and polyphloretin phosphate as non-specific antagonists of the stimulatory effects of different agents on adenylate cyclase from various tissues.

7-oxa-13-prostynoic acid (OPA) and polyphloretin phosphate (PPP) are believed to act as specific antagonists of prostaglandin action. In order to estimate their specificity, the inhibitory effects of these drugs were tested on the activity of adenylate cyclase from several tissues which were stimulated by prostaglandins and several other compounds. In adenylate cyclase preparation from L-fibroblasts both OPA (0.15-1.5 MM) and PPP (0.01-1.0 MG/ML) antagonized not only the stimulatory effects of PGE but also the stimulatory effects of sodium fluoride and increased enzyme activity due to the previous treatment of cell cultures by cholera toxin. Both OPA and PPP produced a dose dependent depression of adenylate cyclase activity to zero values both under basal conditions and after stimulation by sodium fluoride and various hormones in all preparations studied, including rat liver, heart, brain, epididymal adipose tissue, small intestine, renal cortex and renal medulla. The present results indicate that both prostaglandin antagonists may, in higher concentrations, act as nonspecific inhibitors of the catalytic unit of adenylate cyclase rather than specific antagonists of the prostaglandin effects on adenylate cyclase.

Adenylyl Cyclases↗
PubMedDate not supplied

Genetic differences in the resistance of rats to isoprenaline-induced heart lesions.

Two strains of rats were obtained by selective breeding: the IR strain, resistant to isoprenaline-induced myocardial lesions and the IS strain, sensitive to this damage. The IR rats grew more slowly, the weight of their adipose tissue was higher and the weight of m. soleus was less than that of the IS rats. The IR rats had a higher content of triglycerides in the serum and a lower isoprenaline-stimulated lipolytic activity of adipose tissue in vitro. The basal NEFA level in the serum and its rise after the administration of isoprenaline in vivo did not differ between the strains. The IR rats had a higher content of glycogen in the heart and in the muscle. After the administration of isoprenaline the glycogen content decreased more slowly in IR rats. The findings indicate a considerable importance of the glycogen stores in the heart for the resistance of myocardium to damage.

Adipose Tissue↗