Effects of N6-cyclopentyladenosine on afterdepolarizations and triggered activity induced by isoproterenol in guinea pig papillary muscle.
OBJECTIVE
To investigate the effects of N6-cyclopentyladenosine (CPA, selective adenosine A1 receptor agonist) on afterdepolarizations and triggered activity induced by isoproterenol (Iso) in guinea pig papillary muscle.


METHODS
The stable and reproducible early afterdepolarization (EAD) and delayed afterdepolarization (DAD) of guinea pig papillary muscle were induced by Iso 50 nmol.L-1. The parameters of EAD and DAD were recorded using intracellular microelectrodes.


RESULTS
CPA markedly attenuated the development of EAD, DAD, and triggered activity (TA) induced by Iso in guinea pig papillary muscle. The inhibitory effects of CPA on Iso-induced EAD and DAD were antagonized by 8-phenyltheophylline (8-PT) and glibenclamide (Gli).


CONCLUSIONS
ATP-sensitive K+ channels were involved in Iso-induced EAD and DAD, and in the inhibitory effects of CPA on EAD and DAD.
Li
Y L
YL
Department of Physiology, Hebei Medical College, Shijiazhuang, China.
He
R R
RR
D000200:Action Potentials / Q000187:drug effects; D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D004594:Electrophysiology; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D010210:Papillary Muscles / Q000502:physiology; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
C048599:N(6)-cyclopentyladenosine; D013806:Theophylline; C028322:8-phenyltheophylline; D000241:Adenosine; D007545:Isoproterenol; D005905:Glyburide