Functional evidence against the existence of β2-adrenoceptors mediating positive inotropic effects in guinea-pig right ventricular myocardium
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In guinea-pig isolated papillary muscles we studied the positive inotropic effects of the β-adrenoceptor agonists isoprenaline, fenoterol and noradrenaline in the presence and absence of the β1-selective antagonist atenolol and the β2-adrenoceptor antagonist ICI 118.551. In Schild regression analysis pA2 values for either atenolol (7.14–7.16) and ICI 118.551 (6.79–6.84) were independent of the agonists used. These results support the view that the inotropic response in guinea-pig ventricular myocardium is mediated by β1-adrenoceptors only.
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