%0 Journal Article
%T Inibi£¿£¿o da corrente de c¨¢lcio tipo L por tramadol e enanti£¿meros em mi¨®citos card¨ªacos de ratos
%A Medei
%A Emiliano
%A Raimundo
%A Juliana M.
%A Nascimento
%A Jos¨¦ Hamilton M.
%A Trachez
%A Margarete M.
%A Sudo
%A Roberto T.
%A Zapata-Sudo
%A Gisele
%J Arquivos Brasileiros de Cardiologia
%D 2011
%I Sociedade Brasileira de Cardiologia - SBC
%R 10.1590/S0066-782X2011005000091
%X background: tramadol is a centrally acting analgesic, whose mechanism of action involves opioid-receptor activation. previously, we have shown that tramadol and its enantiomers had a negative inotropic effect on the papillary muscle in which the (+)-enantiomer is more potent than (-)- and (¡À)-tramadol. objective: in this study, we investigated the effects of tramadol and its enantiomers on l-type calcium current (ica-l). results: tramadol (200 ¦Ìm) reduced the peak amplitude of ica-l at potentials from 0 to +50 mv. at 0 mv, ica-l was reduced by 33.7 ¡À 7.2%. (+)- and (-)-tramadol (200 ¦Ìm) produced a similar inhibition of ica-l, in which the peak amplitude was reduced by 64.4 ¡À 2.8% and 68.9 ¡À 5.8%, respectively at 0 mv (p > 0.05). tramadol, (+)- and (-)-tramadol shifted the steady-state inactivation of ica-l to more negative membrane potentials. also, tramadol and (+)-tramadol markedly shifted the time-dependent recovery curve of ica-l to the right and slowed down the recovery of ica-l from inactivation. the time constant was increased from 175.6 ¡À 18.6 to 305.0 ¡À 32.9 ms (p < 0.01) for tramadol and from 248.1 ¡À 28.1 ms to 359.0 ¡À 23.8 ms (p < 0.05) for (+)-tramadol. the agonist of ¦Ì-opioid receptor damgo had no effect on the ica-l. conclusion: the inhibition of ica-l induced by tramadol and its enantiomers was unrelated to the activation of opioid receptors and could explain, at least in part, their negative cardiac inotropic effect.
%K tramadol
%K calcium channels
%K l-type
%K myocytes
%K cardiac
%K rats.
%U http://www.scielo.br/scielo.php?script=sci_abstract&pid=S0066-782X2011001300008&lng=en&nrm=iso&tlng=en