Influence Of RAAV1 Mediated β1-AR Gene Overexpression On Metoprolol Antihypertensive Effect Of Spontaneously Hypertensive Rats

Objective:To investigated the effects of overexpressingβ1-AR on metoprolol antihypertension of SHRs.Methods:1. Gene clone was done to amplify the cDNA sequences of betal-AR and then subcloned into mammalian expression vector to obtain the recombinant plasmids pSNAV1/CMV-Adrb1, the recombinant plasmids showed correct identification by gene sequencing were packaged to be the recombinant adeno-associated virus which named rAAV1/CMV-Adrb1.2. After taking out 6 SHRs as rAAV1/CMV-EGFP group,18 SHRs were randomly divided into 3 groups:rAAV1/CMV-Adrb1+ metoprolol Group (n=6), surgical+metoprolol Group (n=6) and surgical+saline Group (n=6), all of them were weekly monitoried blood pressure and adjustde the dose according to weight of SHRs lasting 4 weeks.3. RT-PCR and Real-time RT-PCR were used to assay for detection ofβ1-AR gene mRNA expression, Immunohistochemistry and Western-blot were used for theβ1-AR protein expression.Results:1. Construction and identification of virus vector:The recombinant adeno-associated overexpressingβ1-AR was successfully constructed and the titer was 2.0×1012 v.g./mL2. Theβ1-AR expression comparison of each group:RT-PCR and Real-time RT-PCR results showed that rAAV1/CMV-Adrb1 injection could significantly increaseβ1-AR mRNA expression in myocardial tissue of SHRs (0.587±0.132 vs.0.212±0.075, P<0.05) while Immunohistochemistry and Western-blot results showed that rAAV1/CMV-Adrb1 injection could significantly increase theβ1-AR protein expression in myocardial tissue of SHRs (0.545±0.119 vs.0.421±0.136, P<0.05)3. The antihypertensive effects comprison of each group:After 4 weeks of intervention, systolic blood pressure in the rAAV1/CMV-Adrb1+metoprolol group and the surgical+metoprolol group were significantly lower than the saline group (176.2±8.5mmHg vs.182.5±4.5mmHg vs.198.7±7.0 mmHg, P<0.05); the systolic blood pressure drop pressure amplitude was significantly higher than the sham group (27.8±8.5mmHg vs.16.8±2.5mmHg, P<0.05).Conclusions:1. The rAAV1/CMV-Adrbl is successfully constructed and it can significantly increase the expression ofβ1-AR in myocardial of SHRs.2. The SHRs whoseβ1-AR gene is overexpressed has better antihypertensive response to metoprolol and it may be one of the reason for influencing individual antihypertensive response to metoprolol.