Influence of Ethanol Extract of Ginkgo biloba Leaves on the Isolated Rat Heart Work and Mitochondria Functions

Abstract

In this study, we attempted to elucidate whether the effects of ethanol extract of Ginkgo biloba leaves (GBE) observed previously on isolated rat heart mitochondria may be realized in situ (in case of isolated heart perfused under normal conditions and under ischemia-reperfusion). We found that GBE at low concentrations (0.01, 0.05, and 0.1 mL/mL) does not affect the heart rate and parameters of electrocardiogram (ECG) but produces a small increase in the coronary flow. Higher concentration of GBE (0.2 and 0.3 mL/mL) diminished the heart rate, decreased the coronary flow, and tended to enhance the parameters of ECG. The contractility of isolated rat heart and mitochondrial nicotinamide adenine dinucleotide reduced form fluorescence decreased in a GBE concentration-dependent manner. Mitochondria isolated from hearts pre-perfused with GBE (0.05 mL/mL) for 20 minutes before nonflow global ischemia-reperfusion (45 min/15 min) showed higher respiratory rates with pyruvate + malate in state 2 and state 3, higher respiratory control index, and diminished H 2 O 2 generation compared with untreated group. Higher GBE concentration, 0.4 mL/mL, had no effect on H 2 O 2 generation and did not prevent the ischemiareperfusion-induced decrease of pyruvate + malate oxidation in state 3 but even enhanced it. However, in the case of nonischemic perfusions, this GBE concentration had no significant effect on these parameters of respiratory functions of isolated heart mitochondria.

Electrocardiographic profile of guinea pig heart submitted to Ginkgo biloba extract and its terpenoids

“…This findings corroborating with other studies (Baliutyte et al, 2012), that observed PRi increased induced by this extract. Furthermore, both GA and GB also induced PRi increased suggesting that both GA and BB can be responsible by enhance PRi induced by GBE.…”

“…In the present study, 10 mg/ml, this extract contains only approximately 3.5% of terpenoids of which are 1.8 % of ginkgolides and 1.69% of bilobalide. In recent study, authors use several concentration of Ginkgo biloba, but not show the concentration of extract in grams (mass unity), difficultly the comparison with our research (Baliutyte et al, 2012).…”

“…A B (Baliutyte et al, 2012). However, no correlation was provided between extract effect and its constituents.…”

“…EGb and bilobalide (BB), used at high concentrations, usually produced cardiac arrhythmias and/or sinus arrest in rats (Satoh & Nishida, 2004). Recently, was reported that EGb in high concentrations reduced the contraction force in rat heart and decreased of mitochondrial respiratory function (Baliutyte et al, 2012). However, the authors don´t elucidate what was the compound bioactive responsible for this effect.…”

Effects of standardized extract of Ginkgo biloba leaves EGb761 on mitochondrial functions: mechanism(s) of action and dependence on the source of mitochondria and respiratory substrate

“…The above discussed data provided new information about the direct effects of EGb761 on mitochondrial functions in vitro. It is worth mentioning that many investigations including ours (Baliutyte et al 2012) demonstrate cardioprotective, neuroprotective and other effects of EGb761 applied on isolated perfused organs or/and in vivo (according to our unpublished observation, the treatment of rats per os for 7 days with ethanol extract of Ginkgo biloba leaves, GBE, increased the cytochromes aa3 content in liver mitochondria, and some mitochondrial respiratory parameters, n=7-9). Thus, Ginkgo biloba constituents and/or metabolites may reach/enter the cells and mitochondria and may affect the cellular energy metabolism in vivo.…”