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Biomedical subjects

B Tantini

Publications and source records attributed to B Tantini.

28 records · Page 2Linked to original sources
PubMed1985

Reduced mechanical activity of perfused rat heart following morphine or enkephalin peptides administration.

In the isolated and perfused rat heart, the addition of morphine, methionine-enkephalin or leucine-enkephalin to the coronary perfusate, significantly reduces the mechanical activity by negatively affecting both the heart rate and the developed tension. These effects are dose dependent and maximally evident with leucine-enkephalin. Furthermore all the opioids strongly reduce the activity of isoproterenol-stimulated hearts. The suggestion is made that opioid peptides directly influence the cardiac mechanical activity possibly by interacting with membrane-receptor systems.

Animals↗
PubMed1983

Increased cyclic GMP content in confluent and serum-restricted heart cell cultures exposed to polyamines.

Cyclic AMP (cAMP) and cyclic GMP (cGMP) have been implicated as intracellular signals in the transition from a resting to a growing state. This suggestion comes from observations showing that the addition of growth promoting factors to quiescent cell cultures causes a rapid and transient decrease in cAMP and an increase in cGMP contents [9, 11] and that exogenous cAMP or cGMP congeners reduce or stimulate cell growth respectively [6, 13]. In view of this antagonistic effect elicited by the two nucleotides, it has been suggested that a fall in cAMP/cGMP ratio might be the triggering event for the initiation of cell proliferation [6]. Since polyamines correlate positively with active cell division [7], a possible involvement of these biogenic polycations in the regulation of cellular cyclic nucleotide contents is worthwhile investigating. Our previous reports have shown indeed that in different cultured cell types, spermine, spermidine and putrescine, at relatively low doses, are able to reduce cAMP content [3] by increasing cAMP-dependent phosphodiesterase activity (cAMP-PDE) [4] and to counteract the action of different cAMP-mediated effectors [3]. Besides endogenous polyamines seem to be involved in the cAMP-mediated induction of cAMP-PDE, as observed in heart cell cultures [4]. This report shows that the addition of each individual polyamine to confluent and serum-restricted heart cell cultures, while lowering cAMP content, induces an early and rapid increase of cGMP content by reducing the rate of its degradation.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1979

Polyamines and cellular adenosine 3' :5'-cyclic monophosphate.

The effect of polyamines on the cellular concentrations of cyclic AMP was studied. It was shown that 1 microM-spermine caused a decrease in cyclic AMP in chick-embryo heart cells, chick-embryo fibroblasts, neuroblastoma, glioma and neuroblastoma-glioma hybrid cells, grown in culture. A similar decrease was observed when polyamines were added to cells in the presence of a phosphodiesterase inhibitor or after stimulating the cells with various hormones. Noradrenaline was used in cultures of heart cells, prostaglandin E1 and adenosine for neuroblastoma and neuroblastoma-glioma hybrids, whereas isoproterenol was used for the stimulation of glioma cells. Polyamines at higher concentrations were either without effect or caused a slight increase in cyclic AMP. Spermidine (10 microM) also caused a decrease in cellular cyclic AMP, as did 0.1 microM-putrescine. It is suggested that the effect of polyamines on cellular cyclic AMP may be explained by the effect of these polycations on the activity of cellular phosphodiesterase.

Adenosine↗
PubMed1979

[Effect of different oxygen pressure levels on the transport of alpha-aminoisobutyric acid in myocardial cell cultures].

The activity of aminoacid transport, as measured by alpha-aminoisobutyrate uptake, has been studied in confluent myocardial cell cultures exposed to different oxygen tensions. The results obtained indicate that the rate of cellular uptake and accumulation of the inert aminoacid increase with time as the fraction of oxygen is reduced. When alpha-aminoisobutyrate was added in presence of all other aminoacids of the medium, the effect of oxygen was also evident, suggesting a mechanism which overcomes the competitive action of the other aminoacids assigned to the same transport system of alpha-aminoisobutyrate (A system). The modulation of aminoacid transport activity may represent one of the possible mechanisms by which environmental oxygen affect the rate of cellular protein synthesis.

Aminoisobutyric Acids↗
PubMedDate not supplied

Effect of exogenous phospholipids on protein synthesis in confluent heart cell cultures.

Preincubation for 23 hr of confluent chick embryo heart cell cultures with increasing doses of a phospholipidic complex produces a progressive increase of [14C] leucine uptake and of its incorporation into proteins when compared to control cultures maintained with 0.5% foetal calf serum. Conversely, a longer time of exposure (47 and 71 hr) to the same doses of phospholipids exhibits a negative effect on both parameters. The changes in protein specific activity appear to be due to a real different capability of the cells in utilizing the amino acid taken up rather than to the changes in is endogenous availability.

Animals↗