Role of putrescine on androgen-elicited positive inotropism in the left atrium of rats.
J Cardiovasc Pharmacol
; 52(2): 161-6, 2008 Aug.
Article
in En
| MEDLINE
| ID: mdl-18670363
ABSTRACT
Functional and biochemical studies were performed in isolated left atria of male Wistar rats to study whether endogenous polyamines may mediate androgen-elicited positive inotropism and their relationship with a rise in cAMP during the cardiotonic effect. 5 alpha-Dihydrotestosterone (100 microM) exposure increased intracellular putrescine as determined by HPLC, but it did not increase spermidine and spermine. This effect was antagonized by an inhibitor of ornithine decarboxylase, alpha-difluoromethylornithine (10 mM), suggesting enzyme activation. alpha-Difluoromethylornithine also antagonized androgens-elicited inotropism and the increase in intracellular cAMP. Putrescine (1 to 10 mM) elicited a concentration-dependent positive inotropism associated with the cAMP increase. The prior incubation with putrescine antagonized 5 alpha-dihydrotestosterone-elicited inotropism and did not produce sinergism on intracellular cAMP. Short-term incubation with 5 alpha-dihydrotestosterone or forskolin shifted to the left the cardiotonic effect of isoproterenol, an agonist of beta-adrenoceptors, without any increase in Emax, suggesting that a common mechanism was involved. Therefore, polyamines might modulate the cAMP production associated with the cardiotonic effect of androgens.
Full text:
1
Database:
MEDLINE
Main subject:
Dihydrotestosterone
/
Putrescine
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Atrial Function
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Androgens
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Myocardial Contraction
Limits:
Animals
Language:
En
Year:
2008
Type:
Article