Abstract: Abstract :Objective 　To investigate the effects of oral spironolactone on expression of TNF-αin the myocardiac tissue of spontaneous hypertension rats during t he progressing stage of hytertension. Methods 　Twenty eight 2-weeks- old male spontaneous hypertension rats (SHR) were divided randomly into spironolactone group (SHR-SPIRO , n = 10),and control group (SHR-CON , n = 10) ,sex - age matched Wistar Kyoto rats (WKY group , n = 7) which having normal hypertension were also used as the third group . The spironolactone was solved with distilled water and the animals were weighed once weekly to adjust for drug dosage（20mg/kg.d）.Evaluation were performed after 16 weeks of treatment.The rats were anesthetized at 24-week-old with 1g/kg urethane intraperitoneal. The systolic pressure,diastolic pressure, mean arterial blood pressure were deteced by a tube that was pierced into the carotid artery that was connected with physiological function experimental system. The hearts were rapidly isolated and were cut into two parts. The one was fixed in 10% buffered for immunohistochemistry；The other one was throwed quickly into liquid nitrogen . The TNF-αlevels of left ventricular homogenate were deteced by enzyme linked immunosorbent assay. Results The systelic blood pressure,diastolic blood pressure and mean arterial pressure had no differences in the rats between SHR-SPIRO group and SHR-CON group. (SHR-SPIRO: 174.64±19.6；121.65±19.45；148.4±18. 5 vs SHR-CON: 184.19±8.55；136.76±22.06；150.5±24.5 p＞0.05).but the artery blood pressure of the two groups are higher than the WKY group. The concentration of TNF-α is higer in myocardiac tissue in the SHR-CON group than WKY group(24.52±3.36 vs 1.53±0.21 p＜0.05 ); TNF-α expression decrease significently in SHR-SPIRO group than SHR-CON group(5.9±0.96vs 24.52±3.36 p＜0.05 ).Conclusion 1. The levels of myocardial tissue of SHR is higer than the normal hypertension WKY rats;2.Oral spironolactone can decrease concentration of TNF-α of myocardial tissue in hypertension rats.

Key words: spontaneous hypertension rats, aldosterone, spironolactone, TNF-α, myocardial fibrosis