Effects of intrarenal pelvic infusion of tumour necrosis factor-α and interleukin 1-ß on reno-renal reflexes in anaesthetised rats.

OBJECTIVE: Reno-renal reflexes are disturbed in cardiovascular and hypertensive conditions when elevated levels of pro-inflammatory mediators/cytokines are present within the kidney. We hypothesised that exogenously administered inflammatory cytokines tumour necrosis factor alpha (TNF-α) and interleukin (IL)-1ß modulate the renal sympatho-excitatory response to chemical stimulation of renal pelvic sensory nerves. METHODS: In anaesthetised rats, intrarenal pelvic infusions of vehicle [0.9% sodium chloride (NaCl)], TNF-α (500 and 1000 ng/kg) and IL-1ß (1000 ng/kg) were maintained for 30 min before chemical activation of renal pelvic sensory receptors was performed using randomized intrarenal pelvic infusions of hypertonic NaCl, potassium chloride (KCl), bradykinin, adenosine and capsaicin. RESULTS: The increase in renal sympathetic nerve activity (RSNA) in response to intrarenal pelvic hypertonic NaCl was enhanced during intrapelvic TNF-α (1000 ng/kg) and IL-1ß infusions by almost 800% above vehicle with minimal changes in mean arterial pressure (MAP) and heart rate (HR). Similarly, the RSNA response to intrarenal pelvic adenosine in the presence of TNF-α (500 ng/kg), but not IL-1ß, was almost 200% above vehicle but neither MAP nor HR were changed. There was a blunted sympatho-excitatory response to intrapelvic bradykinin in the presence of TNF-α (1000 ng/kg), but not IL-1ß, by almost 80% below vehicle, again without effect on either MAP or HR. CONCLUSION: The renal sympatho-excitatory response to renal pelvic chemoreceptor stimulation is modulated by exogenous TNF-α and IL-1ß. This suggests that inflammatory mediators within the kidney can play a significant role in modulating the renal afferent nerve-mediated sympatho-excitatory response.

Hydrogen Sulphide Treatment Prevents Renal Ischemia-Reperfusion Injury by Inhibiting the Expression of ICAM-1 and NF-kB Concentration in Normotensive and Hypertensive Rats.

Our main objective was to investigate the effect of chronic administration of hydrogen sulphide donor (sodium hydrosulphide) on the expression of intercellular adhesion molecule-1 (ICAM-1) and concentration of nuclear factor-kappa B (NF-kB) in a renal ischemia-reperfusion injury (IRI) model of WKY and L-nitro-arginine-methyl-ester (L-NAME)-induced hypertensive rats. Sodium hydrosulphide (NaHS) was administered intraperitoneally (i.p.) for 35 days while cystathionine gamma lyase (CSE) inhibitor dL-propargylglycine (PAG) was administered at a single dose of 50 mg/kg. Animals were anesthetised using sodium pentobarbitone (60 mg/kg) and then prepared to induce renal ischemia by clamping the left renal artery for 30 min followed by 3 h of reperfusion. Pre-treatment with NaHS improved the renal functional parameters in both WKY and L-NAME-induced hypertensive rats along with reduction of blood pressure in hypertensive groups. Oxidative stress markers like malondialdehyde (MDA), total superoxide dismutase (T-SOD) and glutathione (GSH) were also improved by NaHS treatment following renal IRI. Levels of ICAM-1 and NF-kB concentration were reduced by chronic treatment with NaHS and increased by PAG administration after renal IRI in plasma and kidney. Treatment with NaHS improved tubular morphology and glomerulus hypertrophy. Pre-treatment with NaHS reduced the degree of renal IRI by potentiating its antioxidant and anti-inflammatory mechanism, as evidenced by decreased NF-kB concentration and downregulation of ICAM-1 expression.

The renal excretory responses to acute renal interstitial angiotensin (1-7) infusion in anaesthetised spontaneously hypertensive rats.

This study investigated the impact of intrarenal angiotensin 1-7 (Ang [1-7]) infusion on renal excretory function in a rat model of hypertension. Eleven-week-old spontaneously hypertensive rats (SHRs, n = 7) and Han Wistar controls (NCR, n = 7) were anaesthetised with sodium pentobarbital (60 mg/kg i.p.) and prepared for the measurement of mean arterial pressure (MAP) and left renal function during renal interstitial infusion of Ang (1-7) (50 ng/min). The kidneys were harvested, the renal cortex and medulla separated, prepared for measurement of Ang II and Ang (1-7) and Western blot determination of AT1 and Mas receptor protein expression. MAP, glomerular filtration rate (GFR), urine flow (UF) and absolute sodium excretion (UNaV) were 109 ± 16 mmHg, 4.4 ± 1.0 mL/min/kg, 102 ± 16 µL/min/kg and 16 ± 3 µmol/min/kg, respectively in the NCR and 172 ± 24 mmHg, 3.4 ± 0.7 mL/min/kg, 58 ± 30 µL/min/kg and 8.6 ± 4.8 µmol/min/kg respectively in the SHR. Ang (1-7) increased UF (31%), UNa V (50%) and fractional sodium excretion (FENa+ ) (22%) in the NCR group (all p < 0.05) but had no effect on GFR in either group. The magnitudes of the Ang (1-7)-induced increases in UF and UNa V were significantly blunted in the SHR group (model × drug p < 0.05). The renal cortical AT1: Mas receptor expression ratio was significantly higher in the SHR group (p < 0.05) but renal Ang II and Ang (1-7) levels were not statistically different between groups. The Ang (1-7)-induced increases in sodium and water excretion were impaired in the SHR group in the context of an unstimulated RAS. The decrease in responsiveness of the SHR kidney to Ang (1-7) appears to be associated with higher levels of AT1 receptor expression in the renal cortex.

Tacrolimus restores the high- and low-pressure baroreflex control of renal sympathetic nerve activity in cisplatin-induced renal injury rats.

NEW FINDINGS: What is the central question of this study? Does immunosuppression restore the baroreflex control of renal sympathetic nerve activity (RSNA) in an animal model of kidney injury? What is the main finding and its importance? Tacrolimus, a calcineurin inhibitor, restored the high- and low-pressure baroreflex control of RSNA following cisplatin-induced renal injury. ABSTRACT: Cisplatin administration causes depression of renal haemodynamic and excretory function and is associated with renal sympatho-excitation and loss of baroreflex regulation of renal sympathetic nerve activity (RSNA). This study investigated whether administration of the immunosuppressant tacrolimus in this cisplatin-mediated renal injury model could restore, or the acute intra-renal infusion of tumour necrosis factor α (TNF-α) could blunt, the high- or low-pressure baroreflex control of RSNA. Groups of control and cisplatin-treated (5 mg kg-1 , i.p. on day 0) rats received either saline or tacrolimus (0.25 mg kg-1  day-1 , i.p.) for 7 days prior to study. Rats were anaesthetised and prepared for measurement of mean arterial pressure (MAP), heart rate (HR) and RSNA. Baroreflex gain curves were generated and the degree of renal sympatho-inhibition determined (area under the curve (AUC) reported as %RSNA min) during acute volume expansion. Intrarenal TNF-α infusion (0.3 µg kg-1  h-1 ) in control rats decreased baroreflex gain by 32% (P < 0.05) compared to intra-renal saline infusion. In the cisplatin group (MAP: 98 ± 14 mmHg; HR: 391 ± 24beats min-1 ), the baroreflex gain for RSNA was 39% (P < 0.05) lower than that for the control group (MAP: 91 ± 7 mmHg; HR: 382 ± 29 beats min-1 ). In cisplatin-treated rats given daily tacrolimus (MAP: 84 ± 12 mmHg; HR: 357 ± 30 beats min-1 ), the baroreflex gain and renal sympatho-inhibition (AUC, 2440 ± 1071 vs. 635 ± 498% min) were restored to normal values. These findings provide evidence for the view that cisplatin administration initiates an injury involving inflammation which may contribute to the deranged baroreflex regulation of RSNA. This phenomenon appears mediated in part via the renal innervation.

Interaction between nitric oxide and renal α1-adrenoreceptors mediated vasoconstriction in rats with left ventricular hypertrophyin Wistar Kyoto rats.

Left ventricular hypertrophy (LVH) is associated with decreased responsiveness of renal α1-adrenoreceptors subtypes to adrenergic agonists. Nitric oxide donors are known to have antihypertrophic effects however their impact on responsiveness of renal α1-adrenoreceptors subtypes is unknown. This study investigated the impact of nitric oxide (NO) and its potential interaction with the responsiveness of renal α1-adrenoreceptors subtypes to adrenergic stimulation in rats with left ventricular hypertrophy (LVH). This study also explored the impact of NO donor on CSE expression in normal and LVH kidney. LVH was induced using isoprenaline and caffeine in drinking water for 2 weeks while NO donor (L-arginine, 1.25g/Lin drinking water) was given for 5 weeks. Intrarenal noradrenaline, phenylephrine and methoxamine responses were determined in the absence and presence of selective α1-adrenoceptor antagonists, 5- methylurapidil (5-MeU), chloroethylclonidine (CeC) and BMY 7378. Renal cortical endothelial nitric oxide synthase mRNA was upregulated 7 fold while that of cystathione γ lyase was unaltered in the NO treated LVH rats (LVH-NO) group compared to LVH group. The responsiveness of renal α1A, α1B and α1D-adrenoceptors in the low dose and high dose phases of 5-MeU, CEC and BMY7378 to adrenergic agonists was increased along with cGMP in the kidney of LVH-NO group. These findings suggest that exogenous NO precursor up-regulated the renal eNOS/NO/cGMP pathway in LVH rats and resulted in augmented α1A, α1B and α1D adrenoreceptors responsiveness to the adrenergic agonists. There is a positive interaction between H2S and NO production in normal animals but this interaction appears absent in LVH animals.

Intrarenal Mas and AT1 receptors play a role in mediating the excretory actions of renal interstitial angiotensin-(1-7) infusion in anaesthetized rats.

NEW FINDINGS: What is the central question of this study? Dietary sodium manipulation alters the magnitude of angiotensin-(1-7) [Ang-(1-7)]-induced natriuresis. The present study sought to determine whether this was related to relative changes in the activity of intrarenal Mas and/or AT1 receptors. What is the main finding and its importance? Angiotensin-(1-7)-induced diuresis and natriuresis is mediated by intrarenal Mas receptors. However, intrarenal AT1 receptor blockade also had an inhibitory effect on Ang-(1-7)-induced natriuresis and diuresis. Thus, Ang-(1-7)-induced increases in sodium and water excretion are dependent upon functional Mas and AT1 receptors. We investigated whether angiotensin-(1-7) [Ang-(1-7)]-induced renal haemodynamic and excretory actions were solely dependent upon intrarenal Mas receptor activation or required functional angiotensin II type 1 (AT1 ) receptors. The renin-angiotensin system was enhanced in anaesthetized rats by prior manipulation of dietary sodium intake. Angiotensin-(1-7) and AT1 and Mas receptor antagonists were infused into the kidney at the corticomedullary border. Mas receptor expression was measured in the kidney. Mean arterial pressure, urine flow and fractional sodium excretion were 93 ± 4 mmHg, 46.1 ± 15.7 µl min-1  kg-1 and 1.4 ± 0.3%, respectively, in the normal-sodium group and 91 ± 2 mmHg, 19.1 ± 3.3 µl min-1  kg-1 and 0.7 ± 0.2%, respectively, in the low-sodium group. Angiotensin-(1-7) infusion had no effect on mean arterial pressure in rats receiving a normal-sodium diet but decreased it by 4 ± 5% in rats receiving a low-sodium diet (P < 0.05). Interstitial Ang-(1-7) infusion increased urine flow twofold and fractional sodium excretion threefold (P < 0.05) in rats receiving a normal-sodium diet and to a greater extent, approximately three- and fourfold, respectively, in rats receiving the low-sodium diet (both P < 0.05). Angiotensin-(1-7)-induced increases in urine flow and fractional sodium excretion were absent in both dietary groups during intrarenal AT1 or Mas receptor inhibition after either losartan or A-779, respectively. Thus, AT1 receptor activation, as well as Mas receptor activation, plays an essential role in mediating Ang-(1-7)-induced natriuresis and diuresis. Whether this is because Ang-(1-7) partly antagonizes AT1 receptors or whether Ang-(1-7)-induced natriuresis is mediated through AT1 -Mas receptor dimerization remains unclear.

Renal targeting potential of a polymeric drug carrier, poly-l-glutamic acid, in normal and diabetic rats.

BACKGROUND AND PURPOSE: Poly-l-glutamic acid (PG) has been used widely as a carrier to deliver anticancer chemotherapeutics. This study evaluates PG as a selective renal drug carrier. EXPERIMENTAL APPROACH: 3H-deoxycytidine-labeled PGs (17 or 41 kDa) and 3H-deoxycytidine were administered intravenously to normal rats and streptozotocin-induced diabetic rats. The biodistribution of these compounds was determined over 24 h. Accumulation of PG in normal kidneys was also tracked using 5-(aminoacetamido) fluorescein (fluoresceinyl glycine amide)-labeled PG (PG-AF). To evaluate the potential of PGs in ferrying renal protective anti-oxidative stress compounds, the model drug 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) was conjugated to 41 kDa PG to form PG-AEBSF. PG-AEBSF was then characterized and evaluated for intracellular anti-oxidative stress efficacy (relative to free AEBSF). RESULTS: In the normal rat kidneys, 17 kDa radiolabeled PG (PG-Tr) presents a 7-fold higher, while 41 kDa PG-Tr shows a 15-fold higher renal accumulation than the free radiolabel after 24 h post injection. The accumulation of PG-AF was primarily found in the renal tubular tissues at 2 and 6 h after an intravenous administration. In the diabetic (oxidative stress-induced) kidneys, 41 kDa PG-Tr showed the greatest renal accumulation of 8-fold higher than the free compound 24 h post dose. Meanwhile, the synthesized PG-AEBSF was found to inhibit intracellular nicotinamide adenine dinucleotide phosphate oxidase (a reactive oxygen species generator) at an efficiency that is comparable to that of free AEBSF. This indicates the preservation of the anti-oxidative stress properties of AEBSF in the conjugated state. CONCLUSION/IMPLICATIONS: The favorable accumulation property of 41 kDa PG in normal and oxidative stress-induced kidneys, along with its capabilities in conserving the pharmacological properties of the conjugated renal protective drugs, supports its role as a potential renal targeting drug carrier.

Cystathione gamma lyase/Hydrogen Sulphide Pathway Up Regulation Enhances the Responsiveness of α1A and α1B-Adrenoreceptors in the Kidney of Rats with Left Ventricular Hypertrophy.

The purpose of the present study was to investigate the interaction between H2S and NO (nitric oxide) in the kidney and to evaluate its impact on the functional contribution of α1A and α1B-adrenoreceptors subtypes mediating the renal vasoconstriction in the kidney of rats with left ventricular hypertrophy (LVH). In rats the LVH induction was by isoprenaline administration and caffeine in the drinking water together with intraperitoneal administration of H2S. The responsiveness of α1A and α1B to exogenous noradrenaline, phenylephrine and methoxaminein the absence and presence of 5-methylurapidil (5-MeU) and chloroethylclonidine (CEC) was studied. Cystathione gamma lyase (CSE), cystathione ß synthase (CBS), 3-mercaptopyruvate sulphar transferase (3-MST) and endothelial nitric oxide synthase (eNOS) were quantified. There was significant up regulation of CSE and eNOS in the LVH-H2S compared to the LVH group (P<0.05). Baseline renal cortical blood perfusion (RCBP) was increased (P<0.05) in the LVH-H2S compared to the LVH group. The responsiveness of α1A-adrenergic receptors to adrenergic agonists was increased (P<0.05) after administration of low dose 5-Methylurapidil in the LVH-H2S group while α1B-adrenergic receptors responsiveness to adrenergic agonists were increased (P<0.05) by both low and high dose chloroethylclonidine in the LVH-H2S group. Treatment of LVH with H2S resulted in up-regulation of CSE/H2S, CBS, and 3-MST and eNOS/NO/cGMP pathways in the kidney. These up regulation of CSE/H2S, CBS, and 3-MST and eNOS/NO/cGMP pathways enhanced the responsiveness of α1A and α1B-adrenoreceptors subtypes to adrenergic agonists in LVH-H2S. These findings indicate an important role for H2S in modulating deranged signalling in the renal vasculature resulting from LVH development.

Up Regulation of cystathione γ lyase and Hydrogen Sulphide in the Myocardium Inhibits the Progression of Isoproterenol-Caffeine Induced Left Ventricular Hypertrophy in Wistar Kyoto Rats.

Hydrogen sulphide (H2S) is an emerging molecule in many cardiovascular complications but its role in left ventricular hypertrophy (LVH) is unknown. The present study explored the effect of exogenous H2S administration in the regression of LVH by modulating oxidative stress, arterial stiffness and expression of cystathione γ lyase (CSE) in the myocardium. Animals were divided into four groups: Control, LVH, Control-H2S and LVH-H2S. LVH was induced by administering isoprenaline (5mg/kg, every 72 hours, S/C) and caffeine in drinking water (62mg/L) for 2 weeks. Intraperitoneal NaHS, 56µM/kg/day for 5 weeks, was given as an H2S donor. Myocardial expression of Cystathione γ lyase (CSE) mRNA was quantified using real time polymerase chain reaction (qPCR).There was a 3 fold reduction in the expression of myocardial CSE mRNA in LVH but it was up regulated by 7 and 4 fold in the Control-H2S and LVH-H2S myocardium, respectively. Systolic blood pressure, mean arterial pressure, pulse wave velocity were reduced (all P<0.05) in LVH-H2S when compared to the LVH group. Heart, LV weight, myocardial thickness were reduced while LV internal diameter was increased (all P<0.05) in the LVH-H2S when compared to the LVH group. Exogenous administration of H2S in LVH increased superoxide dismutase, glutathione and total antioxidant capacity but significantly reduced (all P<0.05) plasma malanodialdehyde in the LVH-H2S compared to the LVH group. The renal cortical blood perfusion increased by 40% in LVH-H2S as compared to the LVH group. Exogenous administration of H2S suppressed the progression of LVH which was associated with an up regulation of myocardial CSE mRNA/ H2S and a reduction in pulse wave velocity with a blunting of systemic hemodynamic. This CSE/H2S pathway exhibits an antihypertrophic role by antagonizing the hypertrophic actions of angiotensin II(Ang II) and noradrenaline (NA) but attenuates oxidative stress and improves pulse wave velocity which helps to suppress LVH. Exogenous administration of H2S augmented the reduced renal cortical blood perfusion in the LVH state.

A critical review of pharmacological significance of Hydrogen Sulfide in hypertension.

In the family of gas transmitters, hydrogen sulfide (H2S) is yet not adequately researched. Known for its rotten egg smell and adverse effects on the brain, lungs, and kidneys for more than 300 years, the vasorelaxant effects of H2S on blood vessel was first observed in 1997. Since then, research continued to explore the possible therapeutic effects of H2S in hypertension, inflammation, pancreatitis, different types of shock, diabetes, and heart failure. However, a considerable amount of efforts are yet needed to elucidate the mechanisms involved in the therapeutic effects of H2S, such as nitric oxide-dependent or independent vasodilation in hypertension and regression of left ventricular hypertrophy. More than a decade of good repute among researchers, H2S research has certain results that need to be clarified or reevaluated. H2S produces its response by multiple modes of action, such as opening the ATP-sensitive potassium channel, angiotensin-converting enzyme inhibition, and calcium channel blockade. H2S is endogenously produced from two sulfur-containing amino acids L-cysteine and L-methionine by the two enzymes cystathionine γ lyase and cystathionine ß synthase. Recently, the third enzyme, 3-mercaptopyruvate sulfur transferase, along with cysteine aminotransferase, which is similar to aspartate aminotransferase, has been found to produce H2S in the brain. The H2S has interested researchers, and a great deal of information is being generated every year. This review aims to provide an update on the developments in the research of H2S in hypertension amid the ambiguity in defining the exact role of H2S in hypertension because of insufficient number of research results on this area. This critical review on the role of H2S in hypertension will clarify the gray areas and highlight its future prospects.

[Nle3,d-Phe6 ]-γ2 -melanocyte-stimulating hormone possesses the renal excretory but not the cardiovascular actions of the native γ2 -melanocyte-stimulating hormone in anaesthetized rats.

The present study compared the cardiovascular and renal actions of γ(2) -melanocyte-stimulating hormone (γ(2) MSH) with those of the synthetic analogue [Nle(3) ,d-Phe(6) ]-γ(2) MSH (NDP-γ(2) MSH) and explored the effects of high dietary salt intake on the renal actions of NDP-γ(2) MSH. Both peptides were infused systemically (3-1000 nmol/kg) and intrarenally (500 fmol/min) into innervated and renally denervated rats fed either a normal (0.4% NaCl) or high-salt (4% NaCl; HS) diet. Mean arterial pressure (MAP), glomerular filtration rate (GFR), urinary sodium excretion (U(N) (a) V), urinary output (UV) and fractional sodium excretion were determined, as was expression of the melanocortin MC(3) receptor in inner medullary collecting duct (IMCD) epithelial cells. Both renal and systemic infusion of γ(2) MSH increased MAP by 23 ± 2% and 54 ± 4%, respectively, but equivalent doses of NDP-γ(2) MSH had no significant pressor effects. Both peptides had similar natriuretic and diuretic effects in rats fed a normal salt diet. However, NDP-γ(2) MSH increased U(N) (a) V and UV by two- to threefold in rats fed the normal salt diet and by six- to sevenfold in rats fed the HS diet. Furthermore, NDP-γ(2) MSH induced a 3.5-fold increase in GFR only in rats fed the HS diet. These renal effects of NDP-γ(2) MSH were not abolished by prior renal denervation. Rats fed the HS diet also exhibited a 4.5-fold increase in MC(3) receptor expression in IMCD epithelial cells. Intrarenal infusion of NDP-γ(2) MSH induced the natriuretic but not the cardiovascular effects exhibited by γ(2) MSH. The renal activities may be attributed to a direct binding of NDP-γ(2) MSH to MC(3) receptors expressed in IMCD cells, leading to a potent natriuretic effect that is independent of renal innervation.

Evidence implicating peroxisome proliferator-activated receptor-γ in the pathogenesis of preeclampsia.

Preeclampsia, a major cause of maternal and perinatal mortality and morbidity, is thought to be attributed, in part, to impaired trophoblast invasion. Peroxisome proliferator-activated receptors are ligand-activated transcription factors expressed in trophoblasts, which regulate the expression of a number of genes involved in cell differentiation and proliferation. We investigated the effect of the administration of a peroxisome proliferator-activated receptor-γ antagonist during uncomplicated pregnancy in rats. Using an intraperitoneal miniosmotic pump, healthy pregnant rats were administered either vehicle or the peroxisome proliferator-activated receptor-γ-specific antagonist, T0070907 (1 mg/kg per day from gestational days 11-15). Rats treated with T0070907 developed key features of preeclampsia, including elevated mean arterial blood pressure, proteinuria, endothelial dysfunction, reduced pup weight, and increased platelet aggregation. T0070907-treated rats had reduced plasma vascular endothelial growth factor and increased plasma soluble fms-like tyrosine kinase 1. Furthermore, increases in total placental soluble fms-like tyrosine kinase 1 mRNA and fms-like tyrosine kinase 1 protein were also demonstrated, suggesting the placenta as the main contributor to the increased circulating levels of soluble fms-like tyrosine kinase 1. The labyrinthine trophoblast in the placentas of T0070907-treated rats were less differentiated, had increased cellular proliferation, and were strongly immunopositive for CD-31 staining, indicating adaptive angiogenesis. The present study suggests that peroxisome proliferator-activated receptor-γ may play a pivotal role in the progression of a healthy pregnancy and may critically regulate the risk of preeclampsia. These findings have important implications regarding the underlying etiology of preeclampsia and potential therapeutic targets.

Peroxisome proliferator-activated receptor-γ as a potential therapeutic target in the treatment of preeclampsia.

Preeclampsia is a multisystemic disorder of pregnancy characterized by hypertension, proteinuria, and maternal endothelial dysfunction. It is a major cause of maternal and perinatal morbidity and mortality and is thought to be attributable, in part, to inadequate trophoblast invasion. Peroxisome proliferator-activated receptor-γ (PPAR-γ) is a ligand-activated transcription factor expressed in trophoblasts, and the vasculature of which activation has been shown to improve endothelium-dependent vasodilatation in hypertensive conditions. We investigated the effects of the administration of a PPAR-γ agonist using the reduced uterine perfusion pressure (RUPP) rat model of preeclampsia. The selective PPAR-γ agonist, rosiglitazone, was administered to pregnant rats that had undergone RUPP surgery. To investigate whether any observed beneficial effects of PPAR-γ activation were mediated by the antioxidant enzyme, heme oxygenase 1, rosiglitazone was administered in combination with the heme oxygenase 1 inhibitor tin-protoporphyrin IX. RUPP rats were characterized by hypertension, endothelial dysfunction, and elevated microalbumin:creatinine ratios. Rosiglitazone administration ameliorated hypertension, improved vascular function, and reduced the elevated microalbumin:creatinine ratio in RUPP rats. With the exception of microalbumin:creatinine ratio, these beneficial effects were abrogated in the presence of the heme oxygenase 1 inhibitor. Administration of a PPAR-γ agonist prevented the development of several of the pathophysiological characteristics associated with the RUPP model of preeclampsia, via a heme oxygenase 1-dependent pathway. The findings from this study provide further insight into the underlying etiology of preeclampsia and a potential therapeutic target for the treatment of preeclampsia.

Renal functional responses to ischaemia-reperfusion injury in normotensive and hypertensive rats following non-selective and selective cyclo-oxygenase inhibition with nitric oxide donation.

1. Acute renal failure develops as a result of periods of renal ischaemia during cardiovascular surgery or hypovolaemic shock. The present study investigated the importance of endogenous prostaglandin production and nitric oxide (NO) in the renal haemodynamic and excretory responses to ischaemia-reperfusion both normally and in the hypertensive state by chronic administration of cyclo-oxygenase (COX) inhibitors. 2. Male Wistar and stroke-prone spontaneously hypertensive rats (SHRSP) were subjected to 30 min renal ischaemia and 2 h reperfusion following 7 day treatment with vehicle, aspirin, NO-aspirin or celecoxib. 3. Renal blood flow was higher in the SHRSP treatment groups. Renal ischaemia increased blood pressure in all Wistar groups except that given aspirin, had no effect in the SHRSP and did not change renal blood flow in any group. Glomerular filtration rate was reduced throughout the reperfusion period in both rat strains. The postischaemic diuresis in the Wistar was enhanced by COX-2 inhibition, but not by aspirin or NO-aspirin. Urine flow increased in SHRSP during the postischaemic period, which was blunted by aspirin and NO-aspirin, but not by celecoxib. There was a postischaemic increase in fractional sodium excretion, the magnitude of which was unaltered by any drug in the Wistar rats, but was blunted by aspirin, NO-aspirin and celecoxib in SHRSP. 4. These results suggest that products of COX activity contribute to the renal responses to ischaemia-reperfusion injury, but in different ways, in SHRSP, which may reflect variations in renal prostaglandin and NO production in the hypertensive state.

Adenoviral delivery of the beta2-adrenoceptor gene in sepsis: a subcutaneous approach in rat for kidney protection.

Successful gene therapy requires gene delivery that is efficient, has an optimal route of administration and has biosafety. The aims of the present study were to evaluate the safety and applicability of the subcutaneous delivery route for adenoviral transgenes containing the human beta(2)-adrenoceptor (adeno-beta(2)-AR) and to investigate whether this approach prevented renal dysfunction in a rat model of endotoxaemic shock induced by LPS (lipopolysaccharide). Subcutaneous administration of adeno-beta(2)-AR (a total of 10(10) viral particles) significantly increased beta-AR density in the kidney, lung and liver, but was without effect on physiological and plasma biochemical parameters. Moreover, this dose of virus did not cause any of the potential toxic responses of viral administration, such as inflammation and tissue TNF (tumour necrosis factor)-alpha expression. Although the LPS challenge caused a decrease in glomerular filtration rate, fractional excretion of sodium and renal beta-AR density in all groups, the reduction in renal function was significantly less in the rats given adeno-beta(2)-AR compared with non-treated rats. Thus, although further evaluation will be required, this initial study demonstrated that the subcutaneous injection of adeno-beta(2)-AR was efficient, comparatively non-pathogenic and potentially therapeutic to deal with acute renal failure associated with sepsis.

beta(2)-Adrenoceptor activation attenuates endotoxin-induced acute renal failure.

Abnormalities in the beta(2)-adrenergic control of organ function have been implicated in the pathogenesis of several disease states, such as septic shock. The objectives of the present study were to define the contribution of beta(2)-adrenoceptors (beta(2)-AR) to normal renal physiology and to investigate whether overexpression of renal beta(2)-AR might be potentially beneficial in preventing progressive renal damage associated with endotoxemia. Adenoviral transgenes containing the human beta(2)-AR (Adeno-beta(2)-AR) were constructed and delivered into the rat kidney by means of intraparenchymal injections. Administration of 10(9) total viral particles of Adeno-beta(2)-AR induced an approximately threefold increase in beta(2)-AR density in the renal tissue, which 2 wk after delivery, enhanced GFR and sodium reabsorption compared with control rats. The enhanced GFR was abolished by the addition of the beta(2)-AR antagonist, ICI 118,551. Administration of lipopolysaccharide (LPS) caused a reduction in GFR, beta(2)-AR density, and cAMP together with enhanced TNF-alpha mRNA in the kidney. In rats overexpressing beta(2)-AR, the reduction in baseline GFR and elevation of TNF-alpha mRNA and leukocyte infiltration into the kidney associated with the endotoxin were blocked. These findings suggested the possibility that a renal-specific overexpression of beta(2)-AR preserves basal renal function in response to a ligand-independent beta(2)-AR activation and that the delivery of Adeno-beta(2)-AR gene is a potential novel therapeutic strategy for treatment of acute renal failure associated with sepsis.

Beta2-adrenoceptor activation inhibits Shiga toxin2-induced apoptosis of renal tubular epithelial cells.

Apoptosis is regulated by several pathways, such as caspases, mitogen activated protein kinase (MAPK) and cAMP/cAMP-dependent protein kinase A (PKA) cascade. This study investigated the effect of beta(2)-adrenoceptor activation on Shiga toxin (Stx)2-induced apoptosis in renal tubular cells and the contribution of these signalling pathways. Cultured human adenocarcinoma-derived tubular cells were exposed to Stx2 (64 pg/mL) for 2-24hr following the addition of the beta(2)-adrenoceptor agonist (terbutaline) to the incubation medium. Stx2-induced apoptosis and its amelioration by beta(2)-adrenoceptor activation was confirmed using DNA degradation assays and by flow cytometry for annexin V, mitochondrial membrane potential and caspase(-3 and -7) activity. Exposure of cells to Stx2 for 24hr increased the DNA fragmentation to 11.6+/-0.9%, compared to 3.3+/-0.2% in control cells (P<0.05) but was decreased to approximately 5-7% (P<0.05) in the presence of terbutaline. Furthermore, Stx2-stimulated apoptosis, detected by TUNEL, annexin V and mitochondrial potential, was inhibited by terbutaline (P<0.05) which was prevented by cAMP-PKA inhibitors and a beta(2)-adrenoceptor antagonist. However, inhibition of Stx2-mediated caspase activity by terbutaline was partially blocked by cAMP-PKA inhibitors. On the other hand, p38MAPK inhibition by terbutaline prevented Stx2-induced apoptosis and caspase activity through a cAMP-independent pathway via beta(2)-adrenoceptor. These data indicate that beta(2)-adrenoceptor activation can inhibit Stx2-induced apoptosis of the cells, which may be caused by a reduction in caspase activity through cAMP-PKA activation and the p38MAPK pathway.