Mixed Aqueous Extract of Salvia Miltiorrhiza Reduces Blood Pressure through Inhibition of Vascular Remodelling and Oxidative Stress in Spontaneously Hypertensive Rats

BACKGROUND/AIMS

Salvia miltiorrhiza (SM) contains four major aqueous active ingredients, which have been isolated, purified and identified as danshensu (DSS), salvianolic acid A (Sal-A), salvianolic acid B (Sal-B) and protocatechuic aldehyde (PAL), totally abbreviated as SABP. Although SM is often used to treat various cardiovascular diseases in traditional Chinese medicine, the efficacy and function of optimal compatibility ratio of SM's active ingredients (SABP) in the prevention and treatment of cardiovascular diseases remain uncertain. This study investigated antihypertensive effect and underlying mechanisms of SABP vs. SM lyophilized powder (SMLP) in spontaneously hypertensive rats (SHR) and to establish the ratio of the optimal compatibility of DSS, Sal-A, Sal-B and PAL in improving cardiovascular functions.

METHODS

The SHRs were treated with either SABP or SMLP and their systolic blood pressures (SBP) were monitored. The isolated thoracic aorta of SHRs was segregated for immunohistochemistry, Hematoxylin-Eosin stain and mRNA and protein expression of NOX4, TGF-β1, Col-I, ET-1, α-SMA and Smad7. Moreover, the adventitial fibroblasts (AFs) were isolated and cultured from SD rats' aorta and the reactive oxygen species (ROS) production was determined after SABP or SMLP treatment.

RESULTS

SABP, but not SMLP, significantly reduced SBP, which were accompanied by the inhibited morphological changes in the thoracic aorta and the reduced mRNA and protein expression of NOX4, TGF-β1, Col-I, ET-1 and α-SMA, but the increased Smad 7 expression in SHRs. Moreover, SABP also resulted in a decreased ROS production in AFs of SD rats.

CONCLUSIONS

These results indicate that SABP, but not SMLP, treatment potently inhibits hypertension through improvements of vascular remodeling and oxidative stress. The present study provides new evidence that the efficacy and function from optimal compatibility ratio of SM active ingredients is much better than its lyophilized powder, which represents a strategy to develop SM's new beneficial effect in improving cardiovascular functions.

Characterization and functions of vascular adventitial fibroblast subpopulations

BACKGROUND

Adventitial fibroblasts have been shown to play an important role in vascular remodeling and contribute to neointimal formation in vascular diseases. However, little is known about adventitial fibroblast subpopulations. This study explored the process of isolating rat thoracic aorta adventitial fibroblast subpopulations and characterized their properties following stimulation with angiotensin II (ANG II), a critical factor involved in cardiovascular diseases such as hypertension.

METHODS

Adventitial fibroblasts were isolated and cultured from rat aorta. Fibroblast subpopulations were individually expanded using cloning ring techniques. Cells were treated with ANG II (10 nM, 100 nM and 1 μM) for 0.5, 1, 1.5, 3, 6, 12, or 24 h, and ANG II-induced proliferation and migration were measured by MTT assay and Transwell. Cells were treated with ANG II (100 nM) in the presence or absence of ANG II receptor antagonists (100 μM), losartan (for AT1) and PD-123319 (for AT2). PreproET-1 mRNA and ET-1 were determined by RT-PCR and ELISA, respectively. Collagen type I was detected by western blotting.

RESULTS

Two major fibroblast subpopulations were found in the adventitia, epithelioid-like cells and spindle-like cells; Although ANG II promotes the growth of both subpopulations, epithelioid-like cell proliferation shows dose-dependency on ANG II from 10 nM to 1 μM, while proliferation of spindle-like cells reaches a peak value following 100 nM ANG II stimulation; ANG II stimulation enhanced epithelioid-like but not spindle-like cell migration; ANG II dose-dependently increased the expression of preproET-1 and collagen type I, and enhanced ET-1 secretion in epithelioid-like but not spindle-like cells, effects abolished by the AT1 receptor antagonist, but not with AT2 receptor antagonist.

CONCLUSION

Adventitial fibroblasts are heterogeneous and epithelioid-like subpopulations with high sensitivity to ANG II stimulation may be implicated in the pathophysiological mechanisms of vascular remodeling, reparative processes and cardiovascular diseases.