The Effects of CCl4 on the Expressions of Aquaporin and Superoxide Dismutase in the Kidney of the Spontaneously Hypertensive Rat / 체질인류학회지

Carbon tetrachloride (CCl4) induces hepatocellular damage, resulting in liver cirrhosis by generating reactive oxygen species (ROS). At the stage of decompensated liver cirrhosis, many patients suffer from the abnormal regulation of sodium and water balance such as ascites. Also, the kidney can be directly damaged by CClCCl4-induced ROS generation. The aquaporin (AQP) is an important transmembrane protein located in the kidney to reabsorb water, and it may be affected by the ROS to alter water balance. ROS is related with the development of hypertension and alteration of antioxidant enzymes. This study was undertaken to investigate the effects of CCl4 on the expression of AQPs (AQP1 and AQP2) and superoxide dismutase (SOD) in the kidney of spontaneously hypertensive rat (SHR) and normotensive Wistar-Kyoto rat (WKY). The SOD is known as a scavenger of ROS, and we hypothesized that oxidative stress in the aged kidneys may be increased by hypertension. Male WKY and SHR were randomly divided into control and CCl4-treated groups at 8, 16 and 24 weeks of age, respectively. The experimental group received olive oil-dissolved CCl4 (1.6 mL/kg) on its back subcutaneous tissue twice a week for 4 weeks, and control animals received olive oil only. After 24 hours following the last injection, blood samples and kidneys were obtained under anesthesia. Renal histopathology was examined by H&E stain, and the expression of AQP1, AQP2, CuZn-SOD and Mn-SOD were evaluated by immunohistochemical methods and Western blot analysis. CCl4 treatment induced the tubular swelling, tubular epithelial atrophy or detachment in both WKY and SHR, and interstitial edema, tubular cast and infiltration of leukocyte in SHR. The BUN levels in both WKY and SHR were increased by CCl4 treatment at 16 weeks of age. The expression of AQP1 were increased by CCl4 treatment at 8 and 24 weeks of age SHR. The expressions of AQP2 in 24 week-old control SHR was decreased compared to 8 week-old control SHR. CCl4 treatment increased the expressions of AQP2 at 8 week-old and 24 week-old SHR, and the increasing of AQP2 was more remakable in advanced age. The expressions of CuZnSOD and MnSOD were increased at 24 week-old control SHR compared to same aged WKY. Whereas the expression of CuZnSOD was increased by CCl4 treatment in 8 week-old SHR, the expression of both CuZnSOD and MnSOD were decreased by CCl4 treatment in 24 week-old SHR. In summary, CCl4-treated SHR showed an increase in AQP expression and a decrease in SODs at the advanced age. These results suggest that CCl4-induced oxidative stress in the aged hypertensive rats may alter water balance via upregulation of AQPs and accelerate renal damage via downregulation of SODs.

Effects of Antihypertensive Protein from Pheretima on Angiotensin Ⅱ and Angiotensin Ⅱ AT_1 Receptor in Spontaneously Hypertensive Rats / 中国药房

OBJECTIVE:To investigate the effects of the antihypertensive protein from Pheretima on blood pressure, angiotensinⅡ and angiotensin Ⅱ AT1 receptor in spontaneously hypertensive rats (SHR).METHODS: The dynamic change of blood pressure in SHR after singel intravenous injection of antihypertensive protein from Pheretima was observed. After intervention with antihypertensive protein from earthworm for 28 d,the levels of blood pressure, angiotensinⅡ and expression of angiotensin Ⅱ AT1 receptor in SHR were detected. RESULTS: Either single intravenous injecion or multiple dosing of the antihypertensive protein from Pheretima could significantly reduce the blood pressure in SHR (P0.05).The expression of angiotensin Ⅱ AT1 receptor in kidney of SHR model increased significanlty compared the normal control (wistar rats), but decreased after the intervention of the antihypertensive protein from Pheretima.CONCLUSION: The antihypertensive protein from Pheretima has antihypertensive effect on SHR. The mechanism may be related to the reduction of angiotensinⅡ level and lowering of the expression of a angiotensin Ⅱ AT1 receptor in kidney.

Comparison of ANG II-mediated Ca2+i, IP3 Production and ATPi in Isolated Renal Proximal Convoluted Tubules of Adult SHR and WKY / 대한신장학회잡지

BACKGROUND: The renin angiotensin syaimstem plays an important role in hypertension. Therefore, the purpose of this study was to investigate the comparison of responsiveness to angiotensin II (ANG II) in isolated renal proximal convoluted tubules of spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats. METHODS: Intracellualr calcium concentration ([Ca2+i) was measured using Fura- 2/AM, inositol trisphosphate (IP3) accumulation was determined by radioimmuno assay and cellular ATP content measured using the microchemilunescene method in renal proximal tubule suspension or isolated renal proximal tubules. RESULTS: When measured the ANG II-induced [Ca2+i, the young rats showed a greater response to ANG II than adult rats in both strains. The ANG II (10-7 M)-induced [Ca2+i transient in the cortical tubule suspension from adult SHR was significantly lower than that in age-matched WKY. In isolated proximal tubule segments, ANG II-induced [Ca2+i increment was only observed in S1 segments. Comparing responsiveness to ANG II in SHR and WKY, similar phenomenon was observed as experiment using tubule suspension. IP3 accumulation by ANG II also attenuated in adult SHR. The 20-minutes incubation without any exogenous substrate in proximal convoluted tubule (S1) significantly decreased cellular ATP content and ANG II (10-7 M) inhibited decrement of cellular ATP level. The effect of ANG II on cellular ATP restoration was disappeared by the treatment with losartan. CONCLUSION: From these results, the responsiveness of ANG II to AT1A receptor is attenuated in the proximal convoluted tubules of adult SHR comparing the age- mached WKY.

Effect of different doses of valsartan on blood pressure and left ventricular hypertrophy in spontaneously hypertensive rats / 中国临床药理学与治疗学

AimTo evaluate the effects of different doses of valsartan on blood pressure and left ventricular hypertrophy in spontaneously hypertensive rats (SHR) . MethodsEighteen SHR(fourteenweek-old, male) were divided into three groups (six rats in each group ): SHR control group in which the rats were fed with normal saline; low dose valsartan group in which the rats were fed with valsartan 8 mg· kg-1 · d-1 and high dose valsartan group in which the rats were fed with valsartan 24 mg · kg -1 · d-1, all for 8 weeks. The rats in the WKY control group(n ＝ 6) were fed with normal saline for 8 weeks. Results SBP, LVM/ BW and TDM of SHR were remarkably lower than those of the control after drug intervention, and the effect on SBP, LVM/ BW and TDM was most remarkable in the high dose valsartan group. ConclusionDifferent doses of valsartan can decrease SBP of SHR and inhibit the progression of ventricular hypertrophy.

Distribution of the Dopamine D1 and D2 Receptor Protein Using Immunohistochemistry in Wistar-Kyoto Rat (WKY) and Spontaneously Hypertensive Rat (SHR) Kidneys / 대한신장학회잡지

The kidney and balances of fluid and volume are the basic components of bloocl pressure control, and the kidney is the primary site that initiates the hypertensive process and is affected by hypertensive vascular disease. In the kidney, the dopamine is a potent natriuretic and vasodilating agent, participat- ing in renal sodium excretion and maintenance of cardiovascular homeostasis. And the dopamine receptors in central nervous system and peripheral organs were identified by physiological, biochernical and radioligand binding techniques. Rut previous morphological and biochemical studies have been unable to characterize or determine the tissue distribution of the dopamine receptor subtypes because no selective ligands are available yet. Furthermore, the cellular distribution of the dopamine receptor subtypes in the rat kidney is not demonstrated well. In the SHR, the ability of exogenous and endogenous renal dopamine to engender a natriuresis is impaired. Since renal dopamine levels in genetic models of hypertension are not lower than their normotensive controls, the impaired intrarenal paracrine effect of dopamine in these animal models of hypertension appears to be receptor or postreceptor mediated. And renal dopamine derives mainly from renal tubular dopamine production and to a lesser extent from dopaminergic nerves. The present study utilizes imrnunohistochemistry with specific antibodies to characterize the renal distribution of dopamine receptor subtypes and recognize the role of dopamine receptor defect in the pathogenesis of hypertension in 14-week-old WKY (mean HP 108+/-5mmHg) and SHR (mean RP 174+/-7 mmHg) kidneys. Also it utilizes antibody of tyrosine hyclroxylase (TH) to recognize the site of the dopamine production mediated by TH using light microscopic immunohistochemistry. In the immunohistochemistry of the WKY kidney, dopamine D1 receptor protein is localized to glomerulus, proximal tubule, distal tubule, renal vessels, cortical and medullary collecting duct. And in the SHR kidney, dopamine D1 receptor protein is localized to glomerulus, distal tubule, renal vessels, cortical and medullary collecting duct, and juxtaglomerular apparatus (JGA). But there is no demonstrable positive reaction in the proximal tubule and weakly positive reactions in the renal arterioles of SHR compared with WKY kidney. In the immunohisto-chemistry of the WKY kidney, dopamine D1 receptor protein is localized to glomerulus, proxirnal tubule, distal tubule, renal vessels, cortical and rnedullary collecting duct. And in the SHR kidney, dopamine D2 receptor protein is localized to glomerulus, distal tubule, renal vessels, cortical and medullary collecting duct, and JGA. So, there is no demonstrable positive reaction in the proximal tubule of SHR compared with WKY. In the glomerulus of the WKY and SHR kidneys, both dopamine D1 and D2 receptors are localized. In the in situ hybridization of the WKY and SHR kidneys, dopamine D and D receptors are only demonstrated at the renal vessels. The positive reaction to TH immunohistochemistry of the WKY and SHR kidneys is only observed in the renal medulla compared with negative reaction on the renal cortex. Considering the excretion of sodium up to 65-70% with volume expansion may be mediated by dopamine D1-like receptors in the proximal tubule, our immunohistochemistry findings for the dopamine receptors may support the failure of natriuretic response in the SHR due to an abnormal dopamine receptor. Also our results rnay mean that the glornerular filtration rate is mediated by both dopamine D1 and Dz receptors comparing with the previous studies that the glomerular filtration rate was mediated by dopamine D2 receptor. I'here are some differences in the receptors expressing sites on the previous radioligand binding and pharmacologic studies, but our results suggest that at least some of the renal dopamine DA and DAz receptors correspond structurally to the central dopamine D1 and D2 receptors. Finally the result of TH immunohisto-chemistry suggests that the production of dopamine in the proximal tubule is not mediated by TH.