Functional effects of polyamines via activation of human β1- and β2-adrenoceptors stably expressed in CHO cells.
Polyamines mediate acute metabolic effects and cardiac hypertrophy associated with β-adrenoceptor stimulation. They may also modulate β-adrenoceptors, causing functional responses in rat atria and tracheal smooth muscle. The aim of this study was to determine whether polyamines interact with human β(1)- and β(2)-adrenoceptors and the functional consequences of such an interaction. Chinese hamster ovary (CHO) cells stably transfected with human β(1)- and β(2)-adrenoceptors were used to evaluate the effect of polyamines binding to β-adrenoceptors, cAMP production and morphological changes, which were pharmacologically validated by investigating the effects of the β-adrenoceptor agonists, isoproterenol and salbutamol. Polyamines interacted with human β(1)- and β(2)-adrenoceptors, as shown by the displacement of [(125)I]iodocyanopindolol in the binding assay. Putrescine showed higher affinity to β(1)- than β(2)-adrenoceptors. Spermidine and spermine produced partial displacement (approximately 50%) and, at the highest concentration, the effect was reversed. Putrescine and spermine acutely increased cAMP and, in a serum-free medium, induced a stellate-like form in cells, which was inhibited by propranolol, a β-blocker. A 10 to 15 h incubation with putrescine produced a spindle-like form and spatial organization via β-adrenoceptor activation, evidenced by the antagonizing effect by propranolol and lack of effect in wild-type CHO cells. Additionally, it decreased cell proliferation independently of β-adrenoceptor activation. Spermine caused cell death via fetal bovine serum-dependent and -independent mechanisms. The results suggest that putrescine may act as a non-selective and low affinity agonist of human β(1)- and β(2)-adrenoceptors, eliciting morphological changes. These findings may be of importance in physiology and in diseases involving β-adrenoceptor functionality.
Meana
Clara
C
Farmacología, Departamento de Medicina, Universidad de Oviedo, Julián Clavería 6, Oviedo 33006, Spain.
Bordallo
Javier
J
Bordallo
Carmen
C
Suárez
Lorena
L
Cantabrana
Begoña
B
Sánchez
Manuel
M
D000818:Animals; D016466:CHO Cells; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005312:Fetal Blood; D006801:Humans; D011485:Protein Binding; D011700:Putrescine / Q000008:administration & dosage / Q000494:pharmacology*; D018342:Receptors, Adrenergic, beta-1 / Q000187:drug effects* / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D013095:Spermidine / Q000008:administration & dosage / Q000494:pharmacology*; D013096:Spermine / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2; D013096:Spermine; D000242:Cyclic AMP; D013095:Spermidine; D011700:Putrescine