Objective    To study the effects of β-blocker carvedilol on the activity of Ca

2+

pump and density of Ca

2+

release channel type 2 ryanodine receptor

(RyR

2

) of myocardial sarcoplasmic reticulum (SR) for the prevention and treatment of chronic heart failure.     Methods    After the rat model of chronic heart failure was established by ligating the left coronary artery

the animals were divided into heart failure group (HF group

n=17) and carvedilol treated group (Carv group

n=18) which receiving intragastric injection of 60 mg·kg

-1

·d

-1

carvedilol 1 week after operation for 10 weeks. Another 18 rats were employed as control with sham operation (SH group). The rats of HF group and SH group were given intragastric injection of 2 ml/d normal saline for the same time period with Carv group. Hemodynamic parameters

activity of SR Ca

2+

pump

B

max

and Kd of [

3

H

]

-ryanodine binding to RyR

2

were determined.     Results    Compared with SH group

left ventricular end-diastolic pressure (LVEDP) in HF group was increased (P0.01)

while their +dp/dt

max

and -dp/dt

max

were decreased significantly (P0.01). The LVEDP was lower but +dp/dt

max

and -dp/dt

max

were significantly higher in Carv group than in HF group (P 0.01). The activity of SR Ca

2+

pump and B

max

in HF group were lower than those in SH group (P0.01)

and those in Carv group were higher than those in HF group (P0.01). There was no significant difference in Kd among the 3 groups (P0.05).     Conclusion    Long-term carvedilol administration for chronic heart failure caused by myocardial infarction improves the activity of  Ca

2+

pump and increases the density of RyR

2

of myocardial SR

and may be associated with the amelioration of the myocardial function and myocardial protection.