TY - JOUR AU - Wang Nan AU - Zhao De-hua AU - Sheng Bao-heng PY - 2016 TI - Positive inotropic effect of apomorphine on guinea pig myocardium is mediated by dopamine DA1 receptors JF - Acta Pharmacologica Sinica; Vol 12, No 3 (May 1991): Acta Pharmacologica Sinica Y2 - 2016 KW - N2 - Dopaminergic agonist apomorphine (Apo, 1-100 mumol.L-1) had a concentration-dependent positive inotropic effect on guinea pig left atria. This effect was not changed obviously when the influences of sympathetic and parasympathetic nerves were eliminated by reserpine and atropine, respectively. Apo had little inotropic action on guinea pig papillary muscles. The time course of positive inotropic effect of Apo was different from that of isoprenaline and phenylephrine. Apo influenced the isometric contraction curves in a different way from isoprenaline. Dopaminergic antagonist haloperidol antagonized the positive inotropic effect of Apo. This effect was also competitively antagonized by dopamine DA1 antagonist SCH 23390. While dopamine DA2 antagonist domperidone, beta-adrenergic antagonist propranolol and alpha-adrenergic antagonist phentolamine did not obviously influence the effect of Apo. We concluded that the positive inotropic effect of Apo was mediated by postsynaptic dopamine DA1 receptors in guinea pig left atria. UR - http://www.chinaphar.com/article/view/5791