Kyosuke Kudo

Olprinone reduces ischemia/reperfusion-induced acute renal injury in rats through enhancement of cAMP.

Activated leukocytes are implicated in development of ischemia/reperfusion (I/R)-induced organ injuries. Phosphodiesterase 3 inhibitors have anti-inflammatory effects by preventing cyclic adenosine monophosphate (cAMP) degradation. We examined the effects of olprinone, a specific phosphodiesterase 3 inhibitor, on I/R-induced acute renal injury model in rats. Forty-five minute renal I/R was induced in uni-nephrectomized rats. Rats were divided into a vehicle group, an olprinone group, and a dibutyril (DB) cAMP group. Olprinone (0.2 μg/kg/minute) infusion began 30 min after reperfusion and continued for 3 h. DBcAMP (5 mg/kg), a stable analog of cAMP, was intraperitoneally administered 5 min after reperfusion to clarify the effect of cAMP in our model. Olprinone reduced the I/R-induced increases in serum levels of blood urea nitrogen and creatinine, and improved histological changes, including acute tubular necrosis in the outer medulla. Hemodynamic status was not affected by olprinone. I/R-induced a decrease in renal tissue blood flow, an increase in renal vascular permeability, and an enhancement of leukocyte activation, reflected by renal tissue levels of myeloperoxidase activity, and the tissue levels of cytokine-induced neutrophil chemoattractant (an equivalent of human interleukin 8) and tumor necrosis factor-α were all significantly decreased by olprinone. Olprinone also increased the renal tissue and plasma levels of cAMP in rats subjected to renal I/R. DBcAMP showed similar effects. Our results indicated that olprinone reduced the I/R-induced acute renal injury, probably by inhibiting leukocyte activation. The effects of olprinone could be explained through its action on cAMP levels.

Activation of Sensory Neurons Reduces Ischemia/Reperfusion-induced Acute Renal Injury in Rats

Background:Prostaglandin I2 (PGI2) produced by endothelial cells improves ischemia/reperfusion–induced acute renal injury by inhibiting leukocyte activation in rats. However, the underlying mechanism(s) of increased PGI2 production is not fully understood. Activation of sensory neurons increases endothelial PGI2 production by releasing calcitonin gene-related peptide (CGRP) in rats with hepatic ischemia or reperfusion. We examined here whether activation of sensory neurons increases PGI2 endothelial production, thereby reducing ischemia/reperfusion-induced acute renal injury. Methods:Anesthetized rats were subjected to 45 min of renal ischemia/reperfusion. Rats were pretreated with CGRP, capsazepine (a vanilloid receptor-1 antagonist), CGRP(8–37) (a CGRP receptor antagonist), or indomethacin (a cyclooxygenase inhibitor), or subjected to denervation of primary sensory nerves before ischemia/reperfusion. Results:Renal tissue levels of CGRP and 6-keto-prostaglandin F1&agr;, a stable metabolite of PGI2, increased after renal ischemia/reperfusion, peaking at 1 h after reperfusion. Overexpression of CGRP was also noted at 1 h after reperfusion. Increases in renal tissue levels of 6-keto-prostaglandin F1&agr; at 1 h after reperfusion were significantly inhibited by pretreatment with capsazepine, CGRP(8–37), and indomethacin. Pretreatment with capsazepine, CGRP(8–37), indomethacin, and denervation of primary sensory nerves significantly increased blood urea nitrogen and serum creatinine levels, renal vascular permeability, renal tissue levels of myeloperoxidase activity, cytokine-induced neutrophil chemoattractant, and tumor necrosis factor-&agr;, and decreased renal tissue blood flow. However, pretreatment with CGRP significantly improved these changes. Conclusions:Our results suggest activation of sensory neurons in the pathologic process of ischemia/reperfusion–induced acute renal injury. Such activation reduces acute renal injury by attenuating inflammatory responses through enhanced endothelial PGI2 production.

Age-dependent responses to renal ischemia-reperfusion injury.

BACKGROUND The incidence of acute kidney injury (AKI) in the elderly population has steadily increased in recent years. Functional recovery after AKI is also impaired in the elderly; however, the mechanism underlying these age-related differences is not well understood. In the present study, we assessed kidney morphology, function, and oxidative stress in young and aged rats after renal ischemia and reperfusion. MATERIALS AND METHODS Young (6- to 7-wk-old) and aged (60- to 65-wk-old) male Wistar rats were divided into four groups based on age and treatment: renal ischemia-reperfusion in young rats (young IR); renal ischemia-reperfusion in aged rats (aged IR); sham treatment in young rats (young control), and sham treatment in aged rats (aged control). Rats were sacrificed 24 h after treatment, serum blood urea nitrogen (BUN) and creatinine (Cre) concentrations were determined, and kidney tissue histology and 8-hydroxydeoxyguanosine (8-OHdG) levels were evaluated. RESULTS After ischemia-reperfusion, serum BUN, and Cre levels were higher in aged rats than in young rats. Reperfusion-induced kidney damage and kidney tissue 8-OHdG levels were also more severe in the aged IR group. Moreover, plasma antioxidant potential was lower in aged IR rats than in young IR rats. CONCLUSIONS Aged rats exhibited reduced antioxidant potential and increased oxidative stress after ischemia-reperfusion. Our findings demonstrate that aged rats experience more severe reperfusion-induced injuries compared with young rats.

Cepharanthine Exerts Anti-Inflammatory Effects Via NF-κB Inhibition in a LPS-Induced Rat Model of Systemic Inflammation

BACKGROUND Systemic inflammatory response syndromes involving sepsis continue to have extremely high mortality rates. Inflammation is difficult to control when it spreads throughout the body and often progresses into multiple organ dysfunction, eventually leading to death. Cepharanthine (CE) is a plant alkaloid that possesses bioactive properties, with various known actions. In the present study, we investigated protective effects of CE in a lipopolysaccharide (LPS)-induced systemic inflammatory response model and examined underlying mechanisms. MATERIALS AND METHODS We intravenously administered LPS (7.5 mg/kg) to male Wistar rats after intraperitoneal injections of either physiologic saline (LPS group) or CE (10 mg/kg; CE + LPS group), or 2 h before intraperitoneal injection of CE (post-CE + LPS group). We then compared changes in serum cytokine and nitrogen oxide levels over time, and performed histologic examinations of the lungs and liver in each group. Using mouse macrophage RAW264.7 cells, we determined the effect of CE on LPS-induced cytokine secretion into the cell culture medium, as well as NF-κB activity. RESULTS The increase in LPS-induced cytokine levels in rat serum was significantly inhibited by CE treatment; this effect was also seen in the post-CE + LPS group. In addition, we observed histologic improvements with CE co-treatment. In vitro, CE inhibited NF-κB activation by inhibiting the IKK pathway. CONCLUSIONS These results suggest that CE exerts protective effects, at least in part, via NF-κB inhibition. CE may thus be a potential agent for treating systemic inflammatory response syndromes such as sepsis.

ETS-GS, a new antioxidant, ameliorates renal ischemia-reperfusion injury in a rodent model.

BACKGROUND Ischemia-reperfusion (I/R) contributes to acute kidney injury (AKI). On the other hand, anti-oxidative drugs help to prevent renal injury caused by I/R. The current study examined whether a new antioxidant, ETS-GS, inhibits reactive oxygen species (ROS) generation and thereby prevents renal I/R injury in rodent models. METHODS Rats with experimentally-induced renal I/R injury were treated concurrently with an intravenous injection of either ETS-GS or saline. Anesthesia was induced with sevoflurane. RESULTS Histologic examination revealed marked reduction of interstitial congestion, edema, inflammation, and hemorrhage in kidney tissue harvested 24 h after ETS-GS treatment. Renal I/R-induced secretion of nitric oxide (NO) in serum was inhibited by ETS-GS treatment. Furthermore, malondialdehyde (MDA) levels in the kidney were significantly lower in ETS-GS-treated rats with renal I/R. Moreover, when murine macrophage-like RAW264.7 cells were stimulated with antimycin A in the presence or absence of simultaneous ETS-GS treatment, ETS-GS decreased ROS levels. CONCLUSIONS Thus, ETS-GS lowered ROS levels in cultured cells, reduced serum NO levels, decreased renal MDA levels, and protected rats against I/R-induced kidney injury. Given these in vitro and in vivo findings, ETS-GS is a strong candidate for future exploration of therapeutic potential in various human I/R diseases.

Anti-inflammatory effects of perioperative intensive insulin therapy during cardiac surgery with cardiopulmonary bypass.

PurposeRecent studies have reported that controlling blood glucose with insulin can suppress systemic inflammation. In the present study, we evaluated how perioperative intensive insulin therapy (IIT) influences the inflammatory response in an artificial pancreas during cardiac surgery with cardiopulmonary bypass.MethodsWe randomly divided the patients undergoing cardiac surgery with cardiopulmonary bypass into two groups: an IIT group (n = 13) and a conventional treatment (CT) group (n = 12). For the IIT group, blood glucose control was initiated with an artificial pancreas at initiation of surgery. Blood glucose was maintained at 100 mg/dl until 24 h postoperatively. Blood samples were collected to determine changes in serum cytokine levels over time.ResultsPatients’ characteristics did not differ significantly between groups. Blood glucose levels were significantly higher in the CT group after surgery. Serum levels of tumor necrosis factor-α, interleukin-6, and high-mobility group box 1 were higher in the CT group than in the IIT group.ConclusionsUse of IIT in the artificial pancreas during the perioperative period signifiantly decreased the inflammatory response. Moreover, we did not find evidence of hypoglycemia in those treated with IIT. This suggests that use of IIT in an artificial pancreas can be safe and effective for critically ill patients.

Use of Imaging Agent to Determine Postoperative Indwelling Epidural Catheter Position

Background Epidural anesthesia is widely used to provide pain relief, whether for surgical anesthesia, postoperative analgesia, treatment of chronic pain, or to facilitate painless childbirth. In many cases, however, the epidural catheter is inserted blindly and the indwelling catheter position is almost always uncertain. Methods In this study, the loss-of-resistance technique was used and an imaging agent was injected through the indwelling epidural anesthesia catheter to confirm the position of its tip and examine the migration rate. Study subjects were patients scheduled to undergo surgery using general anesthesia combined with epidural anesthesia. Placement of the epidural catheter was confirmed postoperatively by injection of an imaging agent and X-ray imaging. Results The indwelling epidural catheter was placed between upper thoracic vertebrae (n = 83; incorrect placement, n = 5), lower thoracic vertebrae (n = 123; incorrect placement, n = 5), and lower thoracic vertebra-lumbar vertebra (n = 46; incorrect placement, n = 7). In this study, a relatively high frequency of incorrectly placed epidural catheters using the loss-of-resistance technique was observed, and it was found that incorrect catheter placement resulted in inadequate analgesia during surgery. Conclusions Although the loss-of-resistance technique is easy and convenient as a method for epidural catheter placement, it frequently results in inadequate placement of epidural catheters. Care should be taken when performing this procedure.

Cepharanthine Improves Renal Ischemia-Reperfusion Injury in Rats

BACKGROUND Acute renal damage has numerous causes, including renal ischemia-reperfusion injury. Due to its diverse actions, cepharanthine is used to treat many acute and chronic diseases, including pit viper bites, alopecia areata, and leucopenia in radiation therapy. In this study, we examined whether cepharanthine provides a renal-protective effect in a renal ischemia-reperfusion model. MATERIALS AND METHODS Male Wistar rats were divided into four groups that received the following treatments: induction of renal ischemia-reperfusion (I/R group); subcutaneous injection of cepharanthine (10 mg/kg) followed 1 h later by induction of renal ischemia-reperfusion (Cepha + I/R group); subcutaneous injection of cepharanthine (10 mg/kg) (Cepha group); and subcutaneous injection of saline followed 1 h later by sham treatment (control group). Rats were sacrificed 24 h after renal ischemia-reperfusion or sham treatment. Serum blood urea nitrogen (BUN) and creatinine (Cre) concentrations were determined, histologic examination was performed, and oxidative stress was evaluated in kidney tissue. In addition, antimycin A (AMA)-stimulated RAW264.7 cells were treated with cepharanthine to determine its antioxidant effects. RESULTS Serum BUN and Cre levels were increased in the I/R group; however, these increases were significantly inhibited in the Cepha + I/R group. Similarly, kidney tissue damage observed in the I/R group was attenuated in the Cepha + I/R group. In vitro, cells treated with both cepharanthine and AMA showed reduced reactive oxygen species activity compared with cells treated with AMA alone. CONCLUSIONS Our findings suggest that cepharanthine may be effective in the treatment of various types of ischemia-reperfusion injuries.

Insulin Treatment of Diabetic Rats Reduces Cardiac Function in a Lipopolysaccharide-Induced Systemic Inflammation Model

BACKGROUND Diabetes is a common comorbidity in patients with various medical conditions. Tight glucose control is known to improve systemic inflammation; however, whether it is effective in diabetic patients is unknown. The purpose of this study was to examine how strict glucose control affects systemic inflammation in diabetic patients. MATERIALS AND METHODS Male Wistar rats. We determined the effect of insulin therapy on cardiac function in a rat model of systemic inflammation. We administered lipopolysaccharide intravenously, with or without insulin, to streptozotocin-induced diabetic rats. After induction of systemic inflammation, we determined serum cytokine (IL-6 and TNFα) and nitrate/nitrite levels and measured cardiac function. RESULTS Cytokine levels and cardiac function were significantly reduced in diabetic rats compared to non-diabetic rats. Moreover, insulin treatment was associated with higher cytokine levels and decreased cardiac function. CONCLUSION In systemic inflammatory conditions, diabetes increases various proinflammatory mediators and inhibits cardiac function; insulin treatment exacerbates these effects. Thus, strict glucose control may not be desirable in diabetic patients with systemic inflammatory conditions.