Calcium channel blocker and renal mitochondrial function in warm renal ischemia

Utilizing pathophysiological concepts of ischemia-reperfusion injury to design renoprotective strategies and therapeutic interventions for normothermic ex vivo kidney perfusion

Normothermic machine perfusion (NMP) has emerged as a promising tool for the preservation, viability assessment, and repair of deceased-donor kidneys prior to transplantation. These kidneys inevitably experience a period of ischemia during donation, which leads to ischemia-reperfusion injury when NMP is subsequently commenced. Ischemia-reperfusion injury has a major impact on the renal vasculature, metabolism, oxygenation, electrolyte balance, and acid-base homeostasis. With an increased understanding of the underlying pathophysiological mechanisms, renoprotective strategies and therapeutic interventions can be devised to minimize additional injury during normothermic reperfusion, ensure the safe implementation of NMP, and improve kidney quality. This review discusses the pathophysiological alterations in the vasculature, metabolism, oxygenation, electrolyte balance, and acid-base homeostasis of deceased-donor kidneys and delineates renoprotective strategies and therapeutic interventions to mitigate renal injury and improve kidney quality during NMP.

Amlodipine alleviates renal ischemia/reperfusion injury in rats through Nrf2/Sestrin2/PGC-1α/TFAM Pathway

BACKGROUND

Previously, observational studies showed that amlodipine can mitigate calcineurin inhibitor- and contrast-induced acute kidney injury (AKI). Herein, we aimed to measure the effect of amlodipine on renal ischemia/reperfusion (I/R) injury and find the underlying mechanisms.

MATERIALS AND METHODS

Bilateral renal I/R was induced by clamping the hilum of both kidneys for 30 min. The first dose of amlodipine 10 mg/kg was gavaged before anesthesia. The second dose of amlodipine was administered 24 h after the first dose. Forty-eight hours after I/R, rats were anesthetized, and their blood and tissue specimens were collected.

RESULTS

Amlodipine significantly decreased the elevated serum levels of creatinine and blood urea nitrogen (BUN) and mitigated tissue damage in hematoxylin & eosin (H&E) staining. Amlodipine strongly reduced the tissue levels of malondialdehyde (MDA), interleukin 1β (IL1β), and tumor necrosis factor α (TNF-α). Amlodipine enhanced antioxidant defense by upregulating nuclear factor erythroid 2-related factor 2 (Nrf2) and Sestrin2. Furthermore, amlodipine significantly improved mitochondrial biogenesis by promoting Sestrin2/peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α)/mitochondrial transcription factor A (TFAM) pathway. It also enhanced autophagy and attenuated apoptosis, evidenced by increased LC3-II/LC3-I and bcl2/bax ratios after renal I/R.

CONCLUSION

These findings suggest that amlodipine protects against renal I/R through Nrf2/Sestrin2/PGC-1α/TFAM Pathway.

Preservation Solutions for Kidney Transplantation: History, Advances and Mechanisms

Solid organ transplantation was one of the greatest medical advances during the past few decades. Organ preservation solutions have been applied to diminish ischemic/hypoxic injury during cold storage and improve graft survival. In this article, we provide a general review of the history and advances of preservation solutions for kidney transplantation. Key components of commonly used solutions are listed, and effective supplementations for current available preservation solutions are discussed. At cellular and molecular levels, further insights were provided into the pathophysiological mechanisms of effective ingredients against ischemic/hypoxic renal injury during cold storage. We pay special attention to the cellular and molecular events during transplantation, including ATP depletion, acidosis, mitochondrial dysfunction, oxidative stress, inflammation, and other intracellular mechanisms.

Study of the protective effect of ischemic and pharmacological preconditioning on hepatic ischemic reperfusion injury induced in rats

Background and Aim

Hepatic ischemia reperfusion injury is the main cause of liver failure following liver surgery, so an effective method is needed to prevent or reduce this hepatic injury. The aim of the present study is to investigate the potential effect of ischemic preconditioning versus pharmacological preconditioning with lisinopril or verapamil for protection against hepatic ischemia reperfusion injury induced in rats.

Methods

Rats were divided into six groups. Group I served as control untreated. Rats of group II were subjected to laparotomy without induction of ischemia reperfusion. Ischemia reperfusion by ligation of the portal trait for 30 min, followed by reperfusion for 2 h, was performed in rats of groups III-VI. Ischemic preconditioning was performed for rats of group IV before induction of ischemia reperfusion. Lisinopril and verapamil was given daily for 3 days before induction of ischemia reperfusion in groups V and VI, respectively. Serum level of liver transaminases and liver malondialdehyde content were measured, and hepatic histopathological examination was assessed.

Results

Induction of ischemia reperfusion resulted in significant elevation of liver transaminases and liver malondialdehyde content associated with significant hepatic histopathological injury that were significantly improved by ischemic preconditioning, lisinopril, or verapamil treatment. Verapamil showed the most significant improvement compared with ischemic preconditioning or lisinopril treatment.

Conclusion

Ischemic preconditioning and pharmacological preconditioning by lisinopril or verapamil can protect against hepatic ischemia reperfusion probably through inhibition of oxidative stress and neutrophil infiltration. The most potent protection is demonstrated by verapamil treatment.

Lovastatin protects mithochondrial and renal function in kidney ischemia-reperfusion in rats

PURPOSE

To investigate the effect of lovastatin on renal ischemia followed by reperfusion.

METHODS

Thirty one Wistar rats submitted to left renal ischemia for 60 minutes followed by contralateral nephrectomy were divided into two groups: A (n =17, control, no treatment), and B (n=14, lovastatin 15 mg/kg/day p.o. ten days before ischemia). The animals were sacrificed at the end of ischemia, after 24 hours and at seven days after reperfusion. Survival, serum urea and creatinine levels and renal mitochondrial function were evaluated.

RESULTS

Mortality was 29.4% in group A and 0.7% in group B. Urea and creatinine levels were increased in both groups, but the values were significantly lower in group B. Mitochondrial function showed decoupling in 83.4% of group A, as opposed to 38.4/% of group B.

CONCLUSIONS

The result shows a protective action of renal function by lovastatin administered before ischemia/reperfusion. Since most of the mitochondrial fraction presented membranes with the ability to maintain ATP production in group B, stabilization of the mitochondrial membrane should be considered as part of the protective action of lovastatin on renal function in ischemia/reperfusion.

Neuroprotective effect of gadolinium: a stretch-activated calcium channel blocker in mouse model of ischemia-reperfusion injury

The present study was designed to investigate the potential of gadolinium, a stretch-activated calcium channel blocker in ischemic reperfusion (I/R)-induced brain injury in mice. Bilateral carotid artery occlusion of 12 min followed by reperfusion for 24 h was given to induce cerebral injury in male Swiss mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using Morris water maze test and motor incoordination was evaluated using rota-rod, lateral push, and inclined beam walking tests. In addition, total calcium, thiobarbituric acid reactive substance (TBARS), reduced glutathione (GSH), and acetylcholinesterase (AChE) activity were also estimated in brain tissue. I/R injury produced a significant increase in cerebral infarct size. A significant loss of memory along with impairment of motor performance was also noted. Furthermore, I/R injury also produced a significant increase in levels of TBARS, total calcium, AChE activity, and a decrease in GSH levels. Pretreatment of gadolinium significantly attenuated I/R-induced infarct size, behavioral and biochemical changes. On the basis of the present findings, we can suggest that opening of stretch-activated calcium channel may play a critical role in ischemic reperfusion-induced brain injury and that gadolinium has neuroprotective potential in I/R-induced injury.

Renal ischemia and reperfusion injury: influence of chorpromazine on renal function and lipid peroxidation

PURPOSE: To evaluate the influence of chlorpromazine (CPZ) on renal function and lipid peroxidation in a rat model of kidney ischemia/reperfusion injury. METHODS: Forty eight Wistar rats underwent a laparotomy for hilar clamping of left kidney with a bulldog clamp for 60 minutes followed by organ reperfusion and contralateral nephrectomy. Of these, 26 received 3mg/kg of CPZ intravenously 15 minutes before renal ischemia (G-E) while the remaining 22 were used as ischemic control group (G-C). Eleven rats of G-E and 8 of G-C were followed for blood urea nitrogen and creatinine determinations before renal ischemia and at 1st, 4th and 7th postoperative days. Samplings of left renal tissue were obtained at 5 minutes (5 rats from each group) and 24 hours (9 G-C and 10 of G-E) of reperfusion for malondialdehy (MDA) content determination. Controls of renal MDA content were determined in kidneys harvested from 6 additional normal rats. RESULTS: Acute renal failure occurred in all animals but levels of BUN and creatinine were significantly lower in G-E (p<0.001). MDA content rose strikingly at 5 minutes of reperfusion in both groups (p>0.05) and returned near to normal levels 24 hours later. CONCLUSION: CPZ conferred partial protection of renal function to kidneys submitted to ischemia/reperfusion injury that seems to be not dependent on inhibition of lipid peroxidation.

Ryanodine receptor antagonism protects the ischemic liver and modulates TNF-alpha and IL-10

BACKGROUND

Dantrolene is a ryanodine receptor and intracellular calcium antagonist. The ryanodine receptor (RyR) Ca(2+) release channel mobilizes Ca(2+) from internal stores to support a variety of cellular functions, including the inflammatory response after ischemia and reperfusion. The pharmacological mechanism of dantrolene is associated with the inhibition of the release of Ca(2+) from the skeletal muscle sarcoplasmic reticulum (SR). We hypothesized that dantrolene could exert a protective effect in our model of liver ischemia and reperfusion by modulating TNF-alpha and IL-10.

MATERIAL AND METHODS

Mice subjected to 90 min of partial (70 to 80%) hepatic ischemia and 3 h of reperfusion were divided into five groups (n = 6/group): sham, ischemic control, and the dantrolene 1 mg/kg group studied at three times of administration: 15 min before reperfusion (DAN-PRE), at the time of reperfusion (DAN-RP), and 15 min after reperfusion (DAN-POS). The parameters measured at 3 h of reperfusion included serum liver function tests alanine aminotransferase (ALT) and aspartate aminotransferase (AST), TNF-alpha, and IL-10 in serum and liver histology.

RESULTS

It was demonstrated that the RyR intracellular calcium antagonist dantrolene offered the most significant protection for the ischemic liver when given before reperfusion and at the time of reperfusion. AST significantly differed between the control group and the DAN-PRE and DAN-RP groups (P < 0.05). ALT showed a statistically significant decrease in the DAN-PRE treated group and a decrease, although not significant, in the DAN-RP. Histological examination demonstrated a significant decrease in vacuolization in the same both groups (P < 0.05). Necrosis was significantly diminished when dantrolene was used at the time of reperfusion; congestion decreased in the same groups but without statistical significant difference. The levels of TNF-alpha were significantly decreased in the DAN-RP group. There was a decrease in TNF-alpha in the DAN-PRE group but not statistically significant. IL-10 reflected the protection observed in necrosis and vacuolization in the histopathology with an increment at the time of reperfusion (P < 0.05). DAN-POS did not exert a protective effect in ALT, AST, liver histology, or cytokine response.

CONCLUSION

For the first time the ryanodine receptor antagonist dantrolene offered significant functional and structural protection of the ischemic liver when given at the time for reperfusion and partial protection when given prereperfusion. RyR inhibition approach down-regulated the expression of TNF-alpha and induced an increment of the protective cytokine IL-10 when administered at the time of reperfusion. There was no protective effect of dantrolene after reperfusion.