In confluent and serum-starved embryonic heart cell cultures, the addition of serum (10%), glucagon (GLU, 0.1 μM) or isoproterenol (ISO, 10 μM), causes the onset of ornithine decarboxylase (ODC) activity, with a maximum after 5-6 hr. This is paralleled by polyamine accumulation and by the induction of TAT, which, in the case of GLU and ISO, exhibits maximal activity at 4-3hr respectively, followed by a net decline. Cyclic AMP (cAMP) also accumulates after exposure to GLU or ISO. However, under different conditions of ODC inhibition, serum fails to induce TAT, thus supporting a relevant role of cellular polyamines in serum action. Conversely, cAMP and TAT responses to GLU or ISO are markedly improved under prevention of polyamine accumulation, which also leads to a longer lasting TAT inducibility. The suggestion is made that polyamines are not required in the cAMP-dependent mechanism of TAT induction, but rather in the restoration of the basal activity of the enzyme. © 1988 Academic Press, Inc.
Study on the role of endogenous polyamines in glucagon, isoproterenol or serum-mediated induction of tyrosine aminotransferase in cultured heart cells / Carlo, C.; Tantini, B.; Marmiroli, S.; Pignatti, C.; Caldarera, C. M.. - In: BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS. - ISSN 0006-291X. - 152:2(1988), pp. 497-504. [10.1016/S0006-291X(88)80065-2]
Study on the role of endogenous polyamines in glucagon, isoproterenol or serum-mediated induction of tyrosine aminotransferase in cultured heart cells
Marmiroli S.;
1988
Abstract
In confluent and serum-starved embryonic heart cell cultures, the addition of serum (10%), glucagon (GLU, 0.1 μM) or isoproterenol (ISO, 10 μM), causes the onset of ornithine decarboxylase (ODC) activity, with a maximum after 5-6 hr. This is paralleled by polyamine accumulation and by the induction of TAT, which, in the case of GLU and ISO, exhibits maximal activity at 4-3hr respectively, followed by a net decline. Cyclic AMP (cAMP) also accumulates after exposure to GLU or ISO. However, under different conditions of ODC inhibition, serum fails to induce TAT, thus supporting a relevant role of cellular polyamines in serum action. Conversely, cAMP and TAT responses to GLU or ISO are markedly improved under prevention of polyamine accumulation, which also leads to a longer lasting TAT inducibility. The suggestion is made that polyamines are not required in the cAMP-dependent mechanism of TAT induction, but rather in the restoration of the basal activity of the enzyme. © 1988 Academic Press, Inc.
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