Objective:

2

To investigate the pharmacological mechanism of Qili Qiangxin Capsule (QLQX) improvement of heart failure (HF) based on miR133a-endoplasmic reticulum stress (ERS) pathway.

Methods:

2

A left coronary artery ligation-induced HF after myocardial infarction model was used in this study. Rats were randomly assigned to the sham group

the model group

the QLQX group [0.32 g/(kg•d)]

and the captopril group [2.25 mg/(kg•d)]

15 rats per group

followed by 4 weeks of medication. Cardiac function such as left ventricular ejection fraction (EF)

fractional shortening (FS)

left ventricular systolic pressure (LVSP)

left ventricular end diastolic pressure (LVEDP)

the maximal rate of increase of left ventricular pressure (+dp/dt max)

and the maximal rate of decrease of left ventricular pressure (–dp/dt max) were monitored by echocardiography and hemodynamics. Hematoxylin and eosin (HE) and Masson stainings were used to visualize pathological changes in myocardial tissue. The mRNA expression of miR133a

glucose-regulated protein78 (GRP78)

inositol-requiring enzyme 1 (IRE1)

activating transcription factor 6 (ATF6)

X-box binding protein1 (XBP1)

C/EBP homologous protein (CHOP) and Caspase 12 were detected by RT-PCR. The protein expression of GRP78

p-IRE1/IRE1 ratio

cleaved-ATF6

XBP1-s (the spliced form of XBP1)

CHOP and Caspase 12 were detected by Western blot. TdT-mediated dUTP nick-end labeling (TUNEL) staining was used to detect the rate of apoptosis.

Results:

2

QLQX significantly improved cardiac function as evidenced by increased EF

FS

LVSP

+dp/dt max

-dp/dt max

and decreased LVEDP (

P

<

0.05

P

<

0.01). HE staining showed that QLQX ameliorated cardiac pathologic damage to some extent. Masson staining indicated that QLQX significantly reduced collagen volume fraction in myocardial tissue (

P

<

0.01). Results from RT-PCR and Western blot showed that QLQX significantly increased the expression of miR133a and inhibited the mRNA expressions of GRP78

IRE1

ATF6 and XBP1

as well as decreased the protein expressions of GRP78

cleaved-ATF6 and XBP1-s and decreased p-IRE1/ IRE1 ratio (

P

<

0.05

P

<

0.01). Further studies showed that QLQX significantly reduced the expression of CHOP and Caspase12

resulting in a significant reduction in apoptosis rate (

P

<

0.05

P

<

0.01).

Conclusion:

2

The pharmacological mechanism of QLQX in improving HF is partly attributed to its regulatory effect on the miR133a-IRE1/XBP1 pathway.