Microcirculatory visualization and metabolomics of Dalbergia cochinchinensis in ameliorating coronary microvascular dysfunction in rats

Abstract

This study employed microcirculation visualization and metabolomics methods to explore the effect and possible mechanism of Dalbergia cochinchinensis in ameliorating coronary microvascular dysfunction(CMD) induced by microsphere embolization in rats. Sixty SPF-grade male SD rats were randomized into sham, model, and low-, medium-, and high-dose [1.5, 3.0, and 6.0 g·kg~(-1)·d~(-1), respectively] D. cochinchinensis water extract groups. The rats in sham and model groups were administrated with equal volume of normal saline by gavage once a day for 7 consecutive days. The rat model of CMD was prepared by injecting polyethylene microspheres into the left ventricle, while the sham group was injected with an equal amount of normal saline. A blood flow meter was used to measure blood flow, and a blood rheometer to measure blood viscosity and fibrinogen content. An automatic biochemical analyzer and reagent kits were used to measure the serum levels of myocardial enzymes, glucose, and nitric oxide(NO). Hematoxylin-eosin(HE) staining was used to observe the pathological changes of myocardial tissue. DiI C12/C18 perfusion was used to infuse coronary microvessels, and the structural and morphological changes were observed using a confocal laser scanning microscope. AngioTool was used to analyze the vascular area, density, radius, and mean E lacunarity in the microsphere embolization area, and vascular blood flow resistance was calculated based on Poiseuille's law. Non-targeted metabolomics based on high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry(UPLC-Q-TOF-MS) was employed screen potential biomarkers and differential metabolites regulated by D. cochinchinensis and the involved metabolic pathways were enriched. The pharmacodynamic results showed that compared with the model group, D. cochinchinensis significantly increased mean blood flow, reduced plasma fibrinogen content, lowered the levels of myocardial enzymes such as creatine kinase(CK), creatine kinase-MB(CK-MB), and lactate dehydrogenase(LDH), alleviate myocardial injury, and protect damaged myocardium. In addition, D. cochinchinensis significantly increased serum NO content, promoted vascular smooth muscle relaxation, dilated blood vessels, lowered serum glucose(GLU) level, improved myocardial energy metabolism, and alleviated pathological changes in myocardial fibrosis and inflammatory cell infiltration. The results of coronary microcirculation perfusion showed that D. cochinchinensis improved the vascular morphology, increased the vascular area, density, and radius, reduced vascular mean E lacunarity and blood flow resistance, and alleviated vascular endothelial damage in CMD rats. The results of metabolomics identified 45 differential metabolites between sham and model groups, and D. cochinchinensis recovered the levels 25 differential metabolites, which were involved in 8 pathways including arachidonic acid metabolism, arginine biosynthesis, and sphingolipids metabolism. D. cochinchinensis can ameliorate coronary microcirculation dysfunction caused by microsphere embolization in rats, and it may alleviate the pathological changes of CMD rats by regulating inflammatory reaction, endothelial damage, and phospholipid metabolism.