[Effects of higeramine on hemodynamics and its tolerability and safety, an experimental study]

To investigate the effects of higeramine (HG) on hemodynamics and its tolerability and safety so as to see if it can be used in cardiac loading test, and to compare the hemodynamic effects of HG and dobutamine (DB).

Six dogs were infused intrevenously with HG in escalating doses from l microgram/kg/min through 2 microgram/kg/min and to 4 microgram/kg/min, each dose being given for 5 minutes. Then the dogs were infused intravenously with DB at the escalating doses from 5 microgram/kg/min through 10 microgram/kg/min to 20 microgram/kg/min, each dose being given for 5 minutes. Heart rate (HR), blood pressure (BP), cardiac output (CO), myocardial oxygen consumption (MOC), and coronary blood flow (CBF) were measured at the beginning of test and by the end of each dose-infusion. Electrocardiography was conducted in the meantime. Left ventricular ejection fraction (LVEF) was measured with radionuclide equilibrium ventriculography. Another 8 dogs were given HG at the escalating doses from 1 microgram/kg/min up to 500 microgram/kg/min, each dose being infused for 3 minutes, to observe the tolerability and safety of HG, HR, BP, and ECG were monitored during the test.

Intravenous administration of HG results in significant inotropic and chronotropic effects on the heart. HR, MOC, CO and CBF all increased in a dose-dependent manner in both HG and DB tests. HG did not cause significant change in systolic blood pressure (SBP), but a slight decrease in diastolic blood pressure (DBP) was found. HR increased steeply to the peak, and then remained at a plateau level. No significant ECG abnormality was seen except a few occasional premature ventricular beats. No dog died during the study.

HG can be used in pharmacological stress test with remarkable tolerability and safety even at the dosage of 500 microgram/kg/min without serious adverse effect. It can be used as an alternative agent to DB under appropriate circumstances.