AIM: To investigate whether stimulation of β-adrenoceptor (AR) and its subtypes augment α1-AR-evoked positive inotropic response and inositol phosphate (InsP) accumulation in isolated rat left atria. METHODS: Inotropic response was determined by contractile function experiment in isolated electrically driven rat left atria. 3H-InsP accumulations were measured by 3H-inositol incorporation and column chromatography. RESULTS: (1) AIM: To investigate whether stimulation of β-adrenoceptor (AR) and its subtypes augment α1-AR-evoked positive inotropic response and inositol phosphate (InsP) accumulation in isolated rat left atria. METHODS: Inotropic response was determined by contractile function experiment in isolated electrically driven rat left atria. 3H-InsP accumulations were measured by 3H-inositol incorporation and column chromatography. RESULTS: (1)