Central angiotensin II-enhanced splenic cytokine gene expression is mediated by the sympathetic nervous system

2005 ◽  
Vol 289 (4) ◽  
pp. H1683-H1691 ◽  
Author(s):  
Chanran K. Ganta ◽  
Ning Lu ◽  
Bryan G. Helwig ◽  
Frank Blecha ◽  
Roman R. Ganta ◽  
...  
Keyword(s):  
Gene Expression ◽  
Angiotensin Ii ◽  
Sympathetic Nerve ◽  
Gene Array ◽  
Cytokine Gene Expression ◽  
Ang Ii ◽  
Cytokine Gene ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Intact Rats

We tested the hypothesis that central angiotensin II (ANG II) administration would activate splenic sympathetic nerve discharge (SND), which in turn would alter splenic cytokine gene expression. Experiments were completed in sinoaortic nerve-lesioned, urethane-chloralose-anesthetized, splenic nerve-intact (splenic-intact) and splenic nerve-lesioned (splenic-denervated) Sprague-Dawley rats. Splenic cytokine gene expression was determined using gene-array and real-time RT-PCR analyses. Splenic SND was significantly increased after intracerebroventricular administration of ANG II (150 ng/kg, 10 μl), but not artificial cerebrospinal fluid (aCSF). Splenic mRNA expression of IL-1β, IL-6, IL-2, and IL-16 genes was increased in ANG II-treated splenic-intact rats compared with aCSF-treated splenic-intact rats. Splenic IL-1β, IL-2, and IL-6 gene expression responses to ANG II were significantly reduced in splenic-denervated compared with splenic-intact rats. Splenic gene expression responses did not differ significantly in ANG II-treated splenic-denervated and aCSF-treated splenic-intact rats. Splenic blood flow responses to intracerebroventricular ANG II administration did not differ between splenic-intact and splenic-denervated rats. These results provide experimental support for the hypothesis that ANG II modulates the immune system through activation of splenic SND, suggesting a novel relation between ANG II, efferent sympathetic nerve outflow, and splenic cytokine gene expression.

Hyperthermia-enhanced splenic cytokine gene expression is mediated by the sympathetic nervous system

2004 ◽  
Vol 19 (2) ◽  
pp. 175-183 ◽  
Author(s):  
Chanran K. Ganta ◽  
Frank Blecha ◽  
Roman R. Ganta ◽  
Bryan G. Helwig ◽  
Sujatha Parimi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mrna Expression ◽  
Gene Array ◽  
Cytokine Gene Expression ◽  
Whole Body ◽  
Cytokine Gene ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Nerve Discharge ◽  
Intact Rats

Whole body hyperthermia (WBH) has been used in experimental settings as an adjunct to radiochemotherapy for the treatment of various malignant diseases. The therapeutic effect of WBH has been hypothesized to involve activation of the immune system, although the effect of hyperthermia-induced activation of sympathetic nerve discharge (SND) on splenic immune function is not known. We tested the hypothesis that heating-induced splenic sympathoexcitation would alter splenic cytokine gene expression as determined using gene array and real-time RT-PCR analyses. Experiments were performed in splenic-intact and splenic-denervated anesthetized Sprague-Dawley rats ( n=32). Splenic SND was increased during heating (internal temperature increased from 38° to 41°C) in splenic-intact rats but remained unchanged in nonheated splenic-intact rats. Splenic interleukin-1β (IL-1β), interleukin-6 (IL-6), and growth-regulated oncogene 1 (GRO 1) mRNA expression was higher in heated than in nonheated splenic-intact rats. Splenic IL-1β, IL-6, and GRO 1 mRNA expression was reduced in heated splenic-denervated compared with heated splenic-intact rats, but did not differ between heated splenic-denervated and nonheated splenic-intact rats. These results support the hypothesis that hyperthermia-induced activation of splenic SND enhances splenic cytokine gene expression.

Abstract 41: Fructose Stimulates Na/H Exchanger 3 Activity and Enhances the Ability of Angiotensin II to Activate Na/H Exchanger 3 in the Proximal Tubule

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Pablo Cabral ◽  
Nancy Hong ◽  
Jeffrey Garvin
Keyword(s):  
Angiotensin Ii ◽  
Proximal Tubule ◽  
Physiological Saline ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Basal Rate ◽  
Low Concentrations ◽  
Sprague Dawley Rats ◽  
High Fructose ◽  
Salt Sensitive Hypertension

Consumption of high-fructose corn syrup as a sweetener has increased dramatically. Fructose has been implicated in the epidemic of diabetes, obesity and hypertension including salt-sensitive hypertension. However, the mechanisms are poorly understood. The proximal nephron reabsorbs 60-70% of the fluid and Na, and most of the filtered bicarbonate via Na/H exchanger 3. Enhanced proximal nephron transport has been implicated in several forms of hypertension. We hypothesized that fructose stimulates NHE3 activity and enhances the ability of angiotensin II (ANG II) to activate NHE3 in the proximal tubule. To test our hypothesis we isolated and perfused proximal tubules from Sprague Dawley rats. NHE3 activity was measured as the recovery of intracellular pH after an NH4Cl acid pulse using the pH sensitive dye BCECF. The rate of pH recovery was measured in Fluorescent Units per second (FU/sec). In the presence of a 5.5 mM glucose-containing physiological saline the basal rate of pH recovery was 3.1 ± 0.8 FU/sec. When the luminal solution was exchanged to a 0.6 mM glucose + 5 mM fructose-containing physiological saline in a second period, the rate of pH recovery increased to 5 ± 1 FU/sec (p<0.03, n=8).To study whether this effect was due to the addition of fructose or the removal of glucose to the lumen, we performed a separate set of experiments where 5 mM glucose was substituted for 5 mM fructose. In the presence of 0.6 mM glucose the basal rate of pH recovery was 3.6 ± 1.5 FU/sec. When 5 mM fructose was added the rate of pH recovery increased to 5.9 ± 2 FU/sec (p<0.02, n=5). Control experiments showed no differences between periods when 5 mm glucose was added back to the luminal perfusate. Finally, we tested the effect of low concentrations of ANG II in the presence or absence of luminal fructose. In the presence of 5.5 mM glucose, ANG II 10-12 M did not affect the rate of pH recovery (change: -1.1 ± 0.5 FU/sec, n=9). However, in the presence of 5 mM fructose, ANG II increased the rate of pH recovery (change: 4.0 ± 2.2 FU/sec, p< 0.03 n=6). We conclude that acute treatment with fructose stimulates NHE3 activity and enhances the ability of ANG II to activate NHE3 in the proximal tubule. These results may partially explain the mechanism by which a fructose diet induces hypertension.

Mechanism of the biphasic arteriolar response to angiotensin II

1984 ◽  
Vol 247 (1) ◽  
pp. H88-H94 ◽  
Author(s):  
J. T. Fleming ◽  
I. G. Joshua
Keyword(s):  
Angiotensin Ii ◽  
Prostaglandin Synthesis ◽  
Krebs Solution ◽  
Ang Ii ◽  
Cremaster Muscle ◽  
Sprague Dawley ◽  
Third Order ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Alpha Chloralose

Male Sprague-Dawley rats (140-180 g) were anesthetized with alpha-chloralose and urethan. The cremaster muscle with intact blood supply and neural innervation was suspended in a tissue bath containing a modified Krebs solution. With the use of television microscopy the luminal diameters of third-order arterioles (14-32 micron) were measured before and after adding angiotensin II (ANG II, bath concn 10(-6) M). The arterioles responded to ANG II with an initial, transient constriction followed by a more prolonged dilation to a diameter larger than the control diameter. Pretreating the muscle with [Sar1, Ile8]ANG II significantly attenuated both the arteriolar constriction and subsequent dilation induced by ANG II. Treatment of the cremaster muscle with mefenamic acid or indomethacin, inhibitors of prostaglandin synthesis, produced a significant reduction in the diameter of the arterioles and abolished the dilator phase of the arteriolar response to ANG II without preventing the ANG II-induced constriction. These results demonstrate that within the intact microcirculation, ANG II produces both an arteriolar constriction and a dilation that are mediated by specific ANG II receptors. The ANG II-induced dilation of the arterioles appears to be caused by increased prostaglandin synthesis and release.

Antihypertensive effect of dietary calcium loading in angiotensin II-salt rats

1991 ◽  
Vol 261 (5) ◽  
pp. R1070-R1074 ◽  
Author(s):  
K. Ando ◽  
Y. Sato ◽  
A. Ono ◽  
K. Takahashi ◽  
T. Shimosawa ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Antihypertensive Effect ◽  
Hypotensive Effect ◽  
Plasma Catecholamine ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Calcium Loading ◽  
Sprague Dawley Rats ◽  
Salt Sensitive Hypertension ◽  
Do So

To clarify the hypotensive effect of high dietary Ca intake on salt-sensitive hypertension, 7-wk-old Sprague-Dawley rats, 3.15% Na and/or 4.07% Ca diet loaded, were administered 125 ng/ml of angiotensin II (ANG II) intraperitoneally for 12 days. Compared with control rats (mean blood pressure 108 +/- 2 mmHg), ANG II administration caused hypertension (131 +/- 4 mmHg, P less than 0.05). Na loading enhanced the hypertensive effect of ANG II (161 +/- 4 mmHg, P less than 0.01). Dietary Ca loading did not significantly inhibit the pressor effect of ANG II alone (119 +/- 4 mmHg). However, Ca loading suppressed hypertension in ANG II-salt rats (126 +/- 4 mmHg, P less than 0.01). Plasma total catecholamine (norepinephrine + epinephrine) was increased in ANG II-salt rats (176 +/- 14 vs. 290 +/- 23 pg/ml, P less than 0.05), but Ca loading decreased plasma catecholamine (182 +/- 13 pg/ml, P less than 0.05). In contrast, plasma catecholamine was not significantly different between ANG II-treated rats with and without Ca loading. Ca loading increased serum Ca in ANG II rats (10.9 +/- 0.1 vs. 11.7 +/- 0.1 mg/dl, P less than 0.05) but did not do so significantly in ANG II-salt rats (10.8 +/- 0.2 vs. 10.9 +/- 0.1 mg/dl). Thus Ca loading exclusively ameliorated salt-sensitive hypertension, which was induced with ANG II administration and Na loading in rats, probably through suppression of the increased sympathetic activity. In addition, these effects of Ca loading were not mediated through an increased blood level of Ca.

Abstract 600: Intrarenal Ghrelin Receptor Antagonism Inhibits cAMP Mediated Angiotensin II Sodium Reabsorption in Normal Rats

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Brandon A Kemp ◽  
Nancy L Howell ◽  
Shetal H Padia
Keyword(s):  
Angiotensin Ii ◽  
Collecting Duct ◽  
Sodium Reabsorption ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Ghrelin Receptor ◽  
Sprague Dawley Rats ◽  
Ghrelin Receptors ◽  
Messenger System

An interaction between angiotensin II (Ang II) and ghrelin has been established in many tissues relevant to cardiovascular control, but nothing is known about their relationship within the kidney. Intrarenal ghrelin receptors (GRs) localize to the collecting duct (CD) where they couple to an adenylyl cyclase second messenger system to increase cAMP and ENaC-dependent Na+ reabsorption. Ang II also stimulates the activity of ENaC in the CD (independent of aldosterone), via actions at AT1Rs. The following studies seek to determine whether CD GRs are an important mechanism of Ang II-induced antinatriuresis. Uninephrectomized Sprague-Dawley rats received 3 cumulative 1h renal interstitial (RI) infusions of vehicle 5% dextrose in water (D5W, N=8), Ang II (2 ng/kg/min, N=8), Ang II + D-LYS-GHRP-6, a highly selective GR antagonist (D-LYS, 2, 4, 6 μg/min, N=8) or D-LYS alone (N=8). Urine Na+ excretion rate (UNaV) was measured each hour and compared to baseline, during which only vehicle was infused. RI fluid was collected each hour for cAMP determinations. RI Ang II induced a significant antinatriuresis (UNaV was reduced by 34% at 1h, P<0.01; by 46% at 2h, P<0.001; and by 56% at 3h, P<0.001 from baseline). Ang II-induced antinatriuresis was accompanied by a significant increase in RI cAMP levels from a baseline value of 2.97±0.56 pmol/mL to 10.9±2.2, 13.4±2.2, and 15.3±2.7 pmol/mL after 1h, 2h, and 3h respectively (all P<0.01). However, each of these effects of RI Ang II infusion was abolished by concurrent GR blockade with D-LYS. These data suggest that intact intrarenal GR activity is necessary for Ang II-induced Na+ reabsorption in vivo. Furthermore, since cAMP fails to increase in response to Ang II when GRs are blocked, (and GRs are known to signal via cAMP in the kidney), these data strongly suggest that one of the mechanisms of Ang II-induced Na+ reabsorption in the kidney is via GR-induced increases in cAMP.

Circulating angiotensin II and drinking behavior in rats

1990 ◽  
Vol 259 (3) ◽  
pp. R531-R538 ◽  
Author(s):  
C. M. Pawloski ◽  
G. D. Fink
Keyword(s):  
Angiotensin Ii ◽  
Water Intake ◽  
Dose Range ◽  
Drinking Behavior ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Physiological Conditions ◽  
Water Drinking ◽  
Sprague Dawley Rats ◽  
Before And After

This study was designed to investigate the effects on water drinking of acute and chronic increases in circulating angiotensin II (ANG II) concentrations in rats. Experiments were conducted in male Sprague-Dawley rats chronically instrumented with femoral arterial and venous catheters and permanently housed in metal metabolism cages. ANG II was infused intravenously either acutely (30 min-2 h) or chronically (3 days) in a dose range of 10-60 ng/min. In no instance did such infusions cause a statistically significant increase in water intake. Other experiments examined the influence of ANG II (10 ng/min iv) on drinking elicited by infusion of hypertonic sodium chloride (1.5 M at 3.5 microliters/min). ANG II administration did not increase drinking to a hypertonic saline stimulus or lower the osmotic threshold for drinking. Nitroprusside (12 micrograms/min) was infused for 30 min to produce hypotension and drinking. Water intake associated with this stimulus was not changed by blocking ANG II formation with enalapril (2 mg/kg iv) or by concomitant infusion of ANG II (10 ng/min iv). Finally, plasma ANG II concentrations were measured before and after 1-h intravenous infusion of saline or ANG II to determine the levels of circulating ANG II produced by the infusion rates used here. It is concluded that the range of circulating ANG II concentrations found under most physiological conditions in rats does not directly stimulate drinking or participate importantly in osmotic or hypotension-induced drinking.

Increased AQP2 targeting in primary cultured IMCD cells in response to angiotensin II through AT1 receptor

2007 ◽  
Vol 292 (1) ◽  
pp. F340-F350 ◽  
Author(s):  
Yu-Jung Lee ◽  
In-Kyung Song ◽  
Kyung-Jin Jang ◽  
Jakob Nielsen ◽  
Jørgen Frøkiær ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Collecting Duct ◽  
Receptor Activation ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Water Reabsorption ◽  
Sprague Dawley Rats ◽  
Medullary Collecting Duct ◽  
Camp Levels

Vasopressin and angiotensin II (ANG II) play a major role in renal water and Na+ reabsorption. We previously demonstrated that ANG II AT1 receptor blockade decreases dDAVP-induced water reabsorption and AQP2 levels in rats, suggesting cross talk between these two peptide hormones ( Am J Physiol Renal Physiol 288: F673–F684, 2005). To directly address this issue, primary cultured inner medullary collecting duct (IMCD) cells from male Sprague-Dawley rats were treated for 15 min with 1) vehicle, 2) ANG II, 3) ANG II + the AT1 receptor blocker candesartan, 4) dDAVP, 5) ANG II + dDAVP, or 6) ANG II + dDAVP + candesartan. Immunofluorescence microscopy revealed that 10−8 M ANG II or 10−11 M dDAVP ( protocol 1) was associated with increased AQP2 labeling of the plasma membrane and decreased cytoplasmic labeling, respectively. cAMP levels increased significantly in response to 10−8 M ANG II and were potentiated by cotreatment with 10−11 M dDAVP. Consistent with this finding, immunoblotting revealed that this cotreatment significantly increased expression of phosphorylated AQP2. ANG II-induced AQP2 targeting was blocked by 10−5 M candesartan. In protocol 2, treatment with a lower concentration of dDAVP (10−12 M) or ANG II (10−9 M) did not change subcellular AQP2 distribution, whereas 10−12 M dDAVP + 10−9 M ANG II enhanced AQP2 targeting. This effect was inhibited by cotreatment with 10−5 M candesartan. ANG II-induced cAMP accumulation and AQP2 targeting were inhibited by inhibition of PKC activity. In conclusion, ANG II plays a role in the regulation of AQP2 targeting to the plasma membrane in IMCD cells through AT1 receptor activation and potentiates the effect of dDAVP on AQP2 plasma membrane targeting.

Hypothermia-enhanced splenic cytokine gene expression is independent of the sympathetic nervous system

2006 ◽  
Vol 291 (3) ◽  
pp. R558-R565 ◽  
Author(s):  
Chanran K. Ganta ◽  
Bryan G. Helwig ◽  
Frank Blecha ◽  
Roman R. Ganta ◽  
Richard Cober ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nervous System ◽  
Sympathetic Nervous System ◽  
Core Temperature ◽  
Chemokine Receptors ◽  
Cytokine Gene Expression ◽  
Pcr Analysis ◽  
Cytokine Gene ◽  
Sympathetic Nervous ◽  
Intact Rats

Splenic nerve denervation abrogates enhanced splenic cytokine gene expression responses to acute heating, demonstrating that hyperthermia-induced activation of splenic sympathetic nerve discharge (SND) increases splenic cytokine gene expression. Hypothermia alters SND responses; however, the role of the sympathetic nervous system in mediating splenic cytokine gene expression responses to hypothermia is not known. The purpose of the present study was to determine the effect of hypothermia on the relationship between the sympathetic nervous system and splenic cytokine gene expression in anesthetized F344 rats. Gene expression analysis was performed using a microarray containing 112 genes, representing inflammatory cytokines, chemokines, cytokine/chemokine receptors and housekeeping genes. A subset of differentially expressed genes was verified by real-time RT-PCR analysis. Splenic SND was decreased significantly during cooling (core temperature decreased from 38 to 30°C) in splenic-intact rats but remained unchanged in sham-cooled splenic-intact rats (core temperature maintained at 38°C). Hypothermia upregulated the transcripts of several genes, including, chemokine ligands CCL2, CXCL2, CXCL10, and CCL20, and interleukins IL-1α, IL-1β, and IL-6. Gene expression responses to hypothermia were similar for the majority of cytokine genes in splenic-intact and splenic-denervated rats. These results suggest that hypothermia-enhanced splenic cytokine gene expression is independent of splenic SND.

Angiotensin II mediates drinking elicited by eating in the rat

1990 ◽  
Vol 258 (2) ◽  
pp. R436-R442 ◽  
Author(s):  
F. S. Kraly ◽  
R. Corneilson
Keyword(s):  
Angiotensin Ii ◽  
Drinking Behavior ◽  
Inhibitory Effect ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Inhibitory Effects ◽  
Physiological Conditions ◽  
Sprague Dawley Rats ◽  
Subcutaneous Dose ◽  
H2 Receptors

Captopril (CA) was used to block synthesis of endogenous angiotensin II (ANG II) in periphery and/or brain of adult male Sprague-Dawley rats in tests for drinking elicited by eating pelleted chow. Blockade of ANG II-converting enzyme (ACE) in periphery alone (using 0.5 mg/kg CA) increased drinking elicited by eating, whereas simultaneous blockade of ACE in periphery and brain (using subcutaneous 100 mg/kg CA or subcutaneous 0.5 mg/kg plus third ventricular 25 micrograms CA) decreased such drinking. The inhibitory effect of 100 mg/kg CA on water-to-food ratio was prevented by a dipsogenically subthreshold subcutaneous dose (5 micrograms/kg) of ANG II. Blockade of ACE in brain alone (third ventricular 25 micrograms CA) had no effect on food-related drinking. Pharmacological antagonism of ANG II (100 mg/kg CA) together with antagonism of histamine H1 and H2 receptors (using intraperitoneal dexbrompheniramine and cimetidine) were not additive in their inhibitory effects on drinking elicited by eating. Blockade of ACE (100 mg/kg CA) inhibited drinking elicited by subcutaneous histamine, but blockade of histamine receptors failed to inhibit drinking elicited by subcutaneous ANG II. These results support a role for endogenous ANG II under what appear to be physiological conditions for drinking behavior, i.e., when drinking is elicited by eating, and they suggest the working hypothesis of ANG II mediation of a histaminergic mechanism for food-related drinking in the rat.

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