ISSN:
1432-1912
Keywords:
Cardiac automaticity
;
Adenosine receptors
;
α-adrenoceptors
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The effects of the non-selective A2 adenosine receptor agonist 5′-N-ethyl-carboxamidoadenosine (NECA) were studied on ventricular automaticity induced by a local injury in the isolated right ventricle of the rat. In concentrations ranging from 0.1 to 100 nM, NECA significantly increased ventricular automaticity. This effect was not apparent when the nonselective α-adrenoceptor blocker phenoxybenzamine was present at a concentration of 10 μM, which antagonizes both α1-and α2-adrenoceptors, as well as when rats were pretreated with reserpine. In non-reserpinized rats, the excitatory effect of NECA was also abolished in the presence of the selective α1-adrenoceptor antagonist prazosin, but not in the presence of the α2-adrenoceptor antagonist idazoxan. In reserpinized rats, the excitatory effect of NECA was restored in the presence of the non specific α-adrenoceptor agonist phenylephrine as well as in the presence of the selective α1-adrenoceptor agonist amidephrine but not in the presence of the selective α2-adrenoceptor agonist clonidine. These results suggest that the excitatory effect of NECA on ectopic ventricular automaticity is dependent on endogenous catecholamines and that α-adrenoceptors of type 1 are, in some way, involved in this effect.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00169368
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