ABSTRACT: n=4 chronically-instrumented conscious male Beagle dogs, dosed with atenolol at 3, 10 and 30 mg/kg, po. No PK phase. Parameters: haemodynamic parameters (SAP, DAP, MAP, HR, LVSP, +dP/dt max, -dP/dt max, LVEDP) and lead II ECG (RR, PR, QRS, QT, QTcB and QTcF intervals). Arterial blood pressure, heart rate and ECG parameters were measured 45, 30 and 15 min before administration (mean of measurements obtained at these time points = baseline; T0) and 30 (T30), 60 (T60), 90 (T90), 120 (T120), 180 (T180), 240 (T240), 480 (T480), 720 (T720) and 1440 min (T1440) post-administration. At each time point indicated above, all parameters were averaged over 10 min.