Polyamines are intracellular messengers in the beta -adrenergic regulation of Ca super(2+) fluxes, (Ca super(2+)) sub(i) and membrane transport in rat heart myocytes

The beta -adrenergic agonist 1-isoproterenol evokes an acute (< 5-10 sec) transient increase in the activity of ornithine decarboxylase (ODC), and the levels of polyamines (putrescine, spermidine, spermine) in acutely isolated rat ventricular myocytes. The ODC inhibitor alpha -difluoromethylornithine (DFMO, 5-10 mM) blocks the isoproterenol-evoked increase in ODC activity and polyamine levels and the changes in super(45)Ca fluxes. The data exclude an increase in (Ca super(2+)) sub(1) in stimulus-transport coupling, and support the hypothesis the polyamines are messengers in beta -adrenoceptor-mediated regulation of transmembrane Ca super(2+) fluxes, (Ca super(2+)) sub(i) and Ca super(2+)-dependent membrane transport.