| BackgroundHydrogen Sulfide (H2S) is regarded as the third endogenous signaling gasotransmitter, besides nitric oxide (NO) and carbon monoxide (CO) , and plays an important role in multi-systems through different mechanisms, such as activation of ATP-sensitive K+ channel (KATP), inhibition of cell proliferation, inflammation development, and anti-oxidative stress, as well as interactions with other endogenous gaseous signaling molecules to cast a strong protective effect in cardiovascular system. The renin-angiotensin system (RAS) plays an important role in regulating the cardiovascular function, affecting the development and outcome of cardiovascular diseases. The tow-kidney and one-clip model (2K1C) activates the RAS system to increase the content of the renin - angiotensin– aldosterone in circulation, causing one side of the renal necrosis, thereby affecting the cardiovascular system of rats.ObjectiveThe purpose of our study is to establish the 2K1C model, observe the myocardial remodeling and fibrous degeneration under the intervention of Hydrogen Sulfide. To study the effects of H2S in regulating of the cardiac structure and function after the activation of the RAS system in vivo with the 2K1C, and to explore its possible mechanisms.Methods44 Male Sprague-Dawley (SD) rats weighing 210±10g were divided randomly into groups as folloews: control group (normal, n=7), sham group(sham surgery, n=7), 2K1C model group (2K1C, n=10), 2K1C+ enalapril group (2K1C+ENA, 5mg/kg/d, n=10), 2K1C+ hydrogen sulfide group (2K1C+H2S, 14umol/kg/d, n=10). Two kidney-one clip (2K1C) renovascular hypertension was induced by placing an acupuncture needle with the internal diameter of 0.25 mm around the left renal artery through a flank incision. The right kidney was left undisturbed. Sham-operated rats underwent the same experimental procedure but no clip was placed. All treatments were started at 8th day after clipping, and continued for 3 months. The hearts were removed and the blood from abdominal artery were collected for the following analyzing: 1. Systolic blood pressure (SBP) of all the rats before the surgery, after the 8th day of surgery and the end of the study was measured by the indirect tail-cuff method; 2.The left ventricle weight/body weight (LVW/BW), the heart weight/body weight (HW/BW), and the left ventricle weight/heart weight (LVW/HW) were measured to assess the myocardial remodeling; 3. The diameter and the cross-sectional area of the myocardial cells from the morphological thought the hematoxylin and eosin (H&E)–stained were observed to determine the cardiac hypertrophy; 4. The expression of myocardial collagen from the morphological thought the Masson–stained were observed to detect the collagen fibers; 5. The expression of AT1 receptors in the myocardial cells was assessed by immunohistochemistry.Results1. There are not statistically significance in SBP of each groups'rats before surgery, the data were 126.17±13.70mmHg,129.23±10.53mmHg,129.25±8.27mmHg(p>0.05). However, 8 days after 2K1C, SBP monitored in the aorta of the rats was increased(p<0.001), and this elevation of blood pressure was also observed in untreated rats at 3 months after operation (untreated 3-month 2K1C rats), SBP increased from 155.02±4.63mmHg to 129.23±10.53mmHg(p<0.001). Treatment with H2S reduced blood pressure, from 157.32±3.56mmHg to 137.11±1.08mmHg(p<0.001), which was still elevated compared to sham-operated rats (p <0.05).2. The left ventricle weight/body weight (LVW/BW), the heart weight/body weight (HW/BW), and the left ventricle weight/heart weight (LVW/HW) of untreated 2K1C rats at 3 months after surgery (untreated 3-month 2K1C rats) were increased by 14% (P<0.001),10% (P<0.001),3% (P<0.001) compared with thoseof age-matched sham-operated rats, and this increase was attenuated by 87%,93%,71% with H2S treatment and attenuated by 65%(P<0.001),66%(P<0.001),58% (P<0.001) with Enalapril treatment ;3. Microscopic analysis of hematoxylin and eosin (H&E)–stained cardiac histological sections revealed a noticeable increase in the cross-sectional area of cardiac myocytes in 3-month 2K1C rats, compared with that in age-matched sham-operated rats. However, 11 week of H2S or Enalapril treatment resulted in the inhibition of myofiber hypertrophy;4. Microscopic analysis of Masson–stained cardiac histological sections revealed a significant increase of blue-stained around the blood vessel wall. The arterial wall was thickened, especially the middle and the endometrial, with a lot of leakage. However, 11 week of H2S or Enalapril treatment resulted in the decreased myocardial collagen hyperplasy ;5. Microscopic analysis of immunohistochemistry cardiac histological sections revealed a noticeable increase of the expression of the AT1 receptors. However, 11 week of H2S or enalapril treatment resulted in the down regulation of the expression of the AT1 receptors.Conclusion1. The blood pressure elevated obviously in the 2K1C rats; Enalapril (5 mg/kg/d) and H2S(14 umol/kg/d) could decrease the blood pressure.2. Fibroglia fibrils in the 2K1C rats'myocytes expressed significantly, and the left ventricle were pachynsis obviously with the myocardial cells reconstruction and fibrosis significantly; but Enalapril and the H2S could decrease the expression of myocardial cells, fall back the left ventricle pachynsis and the myocardial cells reconstruction, anesis the advancement of the myocardial fibrosis.3. The expression of AT1 receptors in myocardial cells were up-regulated significantly in the 2K1C group through activating the RAS system, but Enalapril and H2S inhibited the expression of AT1 receptors in myocytes.4. These results indicate that the effectiveness of the H2S in decreasing the blood pressure, suppressing left ventricle pachynsis and myocardial remodeling, anesising the advancement of the myocardial fibrosis could be possibly related to be rivalry with the pratly myocardial cells, even the menbers of the RAS in the circulation. |
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