Bacopa monnieri extract increases rat coronary flow and protects against myocardial ischemia/reperfusion injury

Background: This study explored Bacopa monnieri, a medicinal Ayurvedic herb, as a cardioprotectant against ischemia/reperfusion injury using cardiac function and coronary flow as end-points. Methods: In normal isolated rat hearts, coronary flow, left ventricular developed pressure, heart rate, and functional recovery were measured using the Langendorff preparation. Hearts were perfused with either (i) Krebs-Henseleit (normal) solution, (control), or with 30, 100 mu g/ml B. monnieri ethanolic extract (30 min), or (ii) with normal solution or extract for 10 min preceding no-perfusion ischemia (30 min) followed by reperfusion (30 min) with normal solution. Infarct volumes were measured by triphenyltetrazolium staining. L-type Ca2+-currents (I-Ca, L) were measured by whole-cell patching in HL-1 cells, a mouse atrial cardiomyocyte cell line. Cytotoxicity of B. monnieri was assessed in rat isolated ventricular myocytes by trypan blue exclusion. Results: In normally perfused hearts, B. monnieri increased coronary flow by 63 +/- 13% (30 mu g/ml) and 216 +/- 21% (100 mu g/ml), compared to control (5 +/- 3%) (n = 8-10, p < 0.001). B. monnieri treatment preceding ischemia/reperfusion improved left ventricular developed pressure by 84 +/- 10% (30 mu g/ml), 82 +/- 10% (100 mu g/ml) and 52 +/- 6% (control) compared to pre-ischemia/reperfusion. Similarly, functional recovery showed a sustained increase. Moreover, B. monnieri (100 mu g/ml) reduced the percentage of infarct size from 51 +/- 2% (control) to 25 +/- 2% (n = 6-8, p < 0.0001). B. monnieri (100 mu g/ml) reduced ICa, L by 63 +/- 4% in HL-1 cells. Ventricular myocyte survival decreased at higher concentrations (50-1000 mu g/ml) B. monnieri. Conclusions: B. monnieri improves myocardial function following ischemia/reperfusion injury through recovery of coronary blood flow, contractile force and decrease in infarct size. Thus this may lead to a novel cardioprotectant strategy.