• The Korean Journal of Physiology
• /
• v.29 no.2
• /
• pp.259-267
• /
• 1995

The renin-angiotensin system plays an important role in the regulation of blood pressure and in body fluid homeostasis. There is increasing evidence for generation of endogenous angiotensin II in many organs and for its role in paracrine functions. Studies were designed to investigate whether hemorrhage produces rapid changes in the gene expression of angiotensinogen in peripheral and brain tissues. Wistar rats received saline drinking water for 7 days, were bled at a rate of $3\;ml\;kg^{-1}\;min^{-1}$ for 7 min, and then decapitated 0, 2, 4, 8, or 24 hr after hemorrhage. Hemorrhage produced a produced hypotension with tachycardia at $2{\pm}8\;hr$, but blood pressure and heart rate had not fully recovered to the basal level at 24 hr. Plasma renin concentration was significantly increased at 2, 4, and 8 hr (maximum sixfold increase at 4 hr) and had returned to the basal level at 24 hr. Renal renin content was significantly increased only at 4 hr after hemorrhage. Angiotensinogen mRNA in both the kidney and liver were stimulated at 2 to 8 hrs, but recovered to the basal level at 24 hr. On the other hand, angiotensinogen mRNA levels il the hypothalamus and brainstem were continuously increased from 2 to 24 hrs. The present study demonstrates the presence of angiotensinogen mRNA in both hepatic and extrahepatic tissues, and more importantly, their up-regulation after hemorrhage. These results suggest that the angiotensinogen-generating systems in the liver, kideny and brain are, at least in part, under independent control and play a local physiological role.

• The Korean Journal of Physiology and Pharmacology
• /
• v.2 no.6
• /
• pp.771-778
• /
• 1998

To investigate interaction of angiotensin converting enzyme (ACE) inhibitor with local tissue renin- angiotensin system (RAS), changes in gene expression of the RAS components in various tissues in response to chronic administration of an ACE inhibitor, enalapril, were examined in Sprague-Dawley male rats. Enalapril was administered in their drinking water $(3{\sim}4\;mg/day)$ over 8 wk. Plasma and renal ACE activity increased significantly after 4 and 8 wk of enalapril treatment. Renin levels of the plasma and kidney of the enalapril-treated rats markedly increased after 4 wk and decreased thereafter, but still remained significantly higher than those of control rats. Kidney mRNA levels of renin markedly increased after 4 and 8 wk of enalapril treatment, but those of angiotensinogen and ANG II-receptor subtypes, $AT_{1A}$ and $AT_{1B}$, did not change significantly. The liver expressed genes for renin, angiotensinogen and $AT_{1A}$ receptor subtype, but $AT_{1B}$ receptor subtype mRNA was not detectable by RT-PCR. None of mRNA for these RAS components in the liver changed significantly by enalapril treatment. The hypothalamus showed mRNA expressions of renin, angiotensinogen, $AT_{1A}$ and $AT_{1B}$ receptor subtypes. $AT_{1A}$ receptor subtype mRNA was more abundant than $AT_{1B}$ receptor subtype in the hypothalamus as shown in the kidney. However, gene expression of the RAS components remained unchanged during 8-wk treatment of enalapril. In the present study, chronic ACE inhibition increased plasma and renal levels of ACE and renin, but did not affect mRNA levels of other RAS components such as angiotensinogen, ANG II receptor subtypes in the kidney. Gene levels of the RAS components in the liver and hypothalamus were not altered by chronic treatment of enalapril. These results suggest the differential expression of the RAS components in response to enalapril, and localized action and some degree of tissue specificity of enalapril.

• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.2
• /
• pp.151-159
• /
• 1997

In an attempt to investigate whether hemorrhage affects the gene expression of the renin-angioteusin system (RAS) components in the brain and peripheral angiotensin-generating tissues, changes in mRNA levels of the RAS components in response to hemorrhage were measured in conscious unrestrained rats. Wistar rats were bled at a rate of 3 ml/kg/min for 5 min, and then decapitated 7 h after hemorrhage. Levels of mRNA for renin, angiotensinogen and angiotensin $II-AT_1$ receptor subtypes ($AT_{1A}$ and $AT_{1B}$) were determined with the methods of northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR). Hemorrhage produced a profound hypotension with tachycardia, but blood pressure and heart rate recovered close to the basal level at 7 h. Plasma and renal renin levels were significantly increased at 7 h. Hemorrhage induced rapid upregulation of gene expression of both $AT_{1A}$ and $AT_{1B}$ receptor subtypes in the brainstem and hypothalamus, downregulation of them in the adrenal gland and liver. However, renin mRNA level increased in the brainstem, decreased in the liver, but was not changed in the hypothalamus, kidney and adrenals after hemorrhage. Angiotensinogen mRNA level was not significantly changed in any of the tissue except a slight increase in the liver. The kidney and liver did not show any significant change in gene expression of the RAS components. These results suggest that gene expression of the RAS in central and peripheral tissues are, at least in part, under independent control and the local RAS in each organ plays specific physiologic role.

• The Korean Journal of Physiology and Pharmacology
• /
• v.3 no.3
• /
• pp.315-320
• /
• 1999

Molecular regulation of the renin-angiotensin system (RAS) was investigated in deoxycorticosterone acetate (DOCA)-salt hypertension. The expression of renin, angiotensinogen and angiotensin II receptor genes in the kidney and liver was determined by Northern blot analysis in rats which were made DOCA-salt hypertensive over the period of 2 or 4 weeks. Along with the hypertension, renin mRNA was decreased in the remnant kidney. The expression of angiotensinogen gene was not significantly altered in the kidney, but was significantly decreased in the liver. The expression of angiotensin II receptor gene was increased in the kidney, while it remained unaltered in the liver. The duration of hypertension did not affect the altered gene expression. It is suggested that the components of RAS are transcriptionally regulated in DOCA-salt hypertension in a tissue-specific manner.

• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.1
• /
• pp.45-53
• /
• 1997

In humans and many animal models with chronic progressive renal diseases, angiotensin-converting enzyme (ACE) inhibitor markedly attenuates the progression of nephropathy. Several studies have reported augmented gene expression and redistribution of renal renin in partial nephrectomized rats. Although precise mechanism(s) is not known, the renin-angiotensin system (RAS) may play an important role in the progression of renal diseases. Thus, this study was undertaken to examine the gene expression of renal renin, angiotensinogen, and $AT_1$ subtypes ($AT_{1A}$ and $AT_{1B}$) in rats with diabetic nephropathy, and the influences of lipopolysaccharide (LPS)-induced septicemia on the gene expression. Four weeks after streptozotocin (STZ) treatment (55 mg/kg, i.p.), rats were randomly divided into LPS-treated (1.6 mg/kg, i.p.) and control rats. At 6 hours after LPS treatment, the rats were killed and the kidney was removed from each rat. Northern blot and reverse transcription-polymerase chain reaction (RT-PCR)techniques were used to detect mRNA expression. STZ treatment markedly attenuated body weight gain and significantly increased blood glucose level. Renal renin content (RRC) was significantly decreased in the STZ-treated rats compared to that in control rats. The renal ACE activity between STZ-treated and control rats was not significantly different. Renal renin mRNA level was prominently increased, while angiotensinogen and $AT_{1A}$ mRNA levels were slightly decreased in STZ-treated rats compared to those in controls. $AT_1$B mRNA level did not differ in both groups. Acute LPS treatment did not show any significant changes of mRNA levels of intrarenal RAS components in both groups. These results suggest that intrarenal RAS components were differentially regulated in STZ-treated diabetic rats. Further studies are required to evaluate the relationship between intrarenal RAS and other vasomodulatory systems.

• Journal of Community Nutrition
• /
• v.8 no.2
• /
• pp.69-75
• /
• 2006

Adipose tissue has now been recognized as a rich source of metabolically active molecules that include leptin and angiotensinogen (AGT), the precursor of angiotensin II (Ang II). Both of which have been implicated in the pathogenesis of metabolic alteration and hypertension associated with obesity. In this study, we examined the relationship between body mass index (BMI), adipocyte size, leptin, Ang II secretion and mRNA expression in human adipose tissue obtained from female subjects. Leptin and Ang II were analyzed using specific radioimmunoassay kits following a 48hour tissue culture. Leptin and Ang II secretion varied from 1.4 - 72.1ng/g and 0.8 - 57.3pg/g of tissue respectively. These large individual variations limit significant correlation between BMI, leptin and Ang II secretion. Ang II secretion was significantly higher in the obese than the non-obese (p < 0.05) and positively correlated with BMI. However, no difference in leptin secretion between the obese and the non-obese was observed and leptin secretion showed negative correlation with BMI. No difference in leptin and AGT mRNA expression in adipose tissue between the obese and the non-obese was observed. Although several limitations of this study, we found increased Ang II secretion in obese patients compared with non-obese patients, and positive correlation between AGT and BMI. Observed difference in AGT expression between the obese and the non-obese in this study might be of importance in relation with obesity related hypertension. (J Community Nutrition 8(2): 69-75, 2006)