| Chronic heart failure (CHF) is a syndrome caused by dysfunction of the heart, and is the severe stage of many cardiovascular diseases. It remains a major health problem in most parts of the world. Researchers attach much importance to the solution of this problem.Treatment of CHF in clinical works still faces many problems: 1) digitalis may bring adverse effects to the cardiomyocytes; 2) Ca2+ antagonism may retain more fluid and sodium in the body; 3)the use of diuretics for a long time may lead to disturbance of electrolyte balance. In addition, long-time medication becomes a heavy economic burden for the patients. At present, the half-life of the medication for the treatment of CHF is usually no more than 24 hours. It is reported that only 27% of those who take the treatment can adhere to medications stipulated by the doctors. It is therefore crucial for scientists to find more reasonable and effective therapies and strategies for the treatment of CHF. Adrenomedullin (ADM) is a peptide isolated from human pheochromocytoma by Kitamura a decade ago. It has undergone intensive investigations in the ensuing years. ADM is now considered a new member of vasodilating and natriuretic peptides that play an important role in the regulation of cardiovascular as well as renal activities. ADM gene was deemed as an endogenous peptide playing crucial role in the treatment of cardiovascular diseases including hypertension and heart failure. Therefore, ADM has been considered a valuable target gene for gene therapy in hypertension and heart failure. At the same time, as the short half-life of ADM is the restriction for its clinical use, the exploration of ways by which ADM can be expressed and produced in vivo becomes an intriguing approach to the subject.This paper is composed of six parts.1, ADM cDNA was inserted into mammalian expressing vector pcDNA3.1, and in vitro expression of ADM was carried out in cultured K562 cell line, which does not express ADM under normal conditions. ADM cDNA was amplified by RT-PCR from the total RNA isolated from the adrenal glands of rats and was inserted into the pcDNA3.1 vector to form pcDNA3.1ADM. The recombinant pcDNA3.1ADM was then transferred into cultured K562 cell line by liposome. The expression of ADM in pcDNA3.1ADM transferred cell was identified by RT-PCR and dot immunoblot assay (DIA). The results demonstrated that there was ADM mRNA in the pcDNA3.1ADM- transferred K562 cell line and ADM peptides in the culturing medium. These results indicated that the recombinant pcDNA3.1ADM vector could express ADM in mammalian cell line.2, BCA was used to quantify overall protein produced by the cultured cardiomyocytes in vitro. The results showed that the total protein production increased in the Group 2 cardiomyocytes which were treated with ANGⅡ; while the cardiomyocytes of Group 3, which was treated with 10-7 mol/L ANGⅡ and pcDNA3.1ADM, produced less protein, as compared with that of Group 2. The results indicated that pcDNA3.1ADM could partially antagonize the protein synthesis induced by ANGⅡ in the cardiomyocytes.3, Rats with left descending coronary artery ligation-induced dysfunction of heart were used in the present study. Ultrasonic imaging analysis and traditional intraventricular catheter recordings were used to evaluate heart function of the rats. Metabolic cages were used to collect urine excreted in 24 hrs. Urine samples were assayed for volume and urinary sodium concentration. We set up 5 groups in our experiment. Group 1 was sham-operated rats, which served as control. Rats with left descending coronary artery ligation were randomly divided into 4 groups five weeks after the surgery, Group 2, Group 3, Group 4, Group 5. The results showed that 5 weeks after the left descending coronary artery ligation the rats in Group 2, 3, 4, 5, exhibited obvious cardiac dysfunction, compared with those sham-operated rats in Group 1, showing an increase in central venous pressure (CVP) and heart rate (HR), a decrease in mean arterial pressure (MAP) and ±dp/dtmax. Whil... |
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