Hemodynamic actions of guan-fu base A in anesthetized rats

Guan-fu base A (GFA) is a terpenoid alkaloid isolated from the tuber of Aconitum coreanum in this institute. GFA exhibited anti-arrhythmic effects in various experimental arrhythmia animal models, and bradycardic actions. In this paper, the hemodynamic action of GFA was investigated. GFA 20 mg.kg-1 iv decreased in heart rate from 420 +/- 51 to 305 +/- 60 bpm (P less than 0.05). The changes of SBP, DBP, LVSP, +/- dP/dtmax, and LVEDP were much smaller or insignificant. GFA (1, 3, 10, 30, 60 mg.kg-1 cumulative iv) increased the heart periods (HP) and QT-intervals in a dose-dependent manner, accompanied by a small increase in PQ-interval, but did not affect QRS complex. The increase in HP from 138 +/- 11 to 321 +/- 48 ms (P less than 0.01) was mainly due to a prolongation of the diastolic period from 22 +/- 12 ms to 156 +/- 46 ms (P less than 0.01). The triple product of HR x LVET x SBP was also decreased with every dose of GFA. This hemodynamic profile suggests that the bradycardic action of GFA can reduce myocardial oxygen consumption and improve myocardial blood supply, which may be of use in certain cardiac patients.