Last year ~34% of donor kidneys were discarded due in part to injury that occurs during cold storage (CS), leading to a high mortality of patients waiting for transplantation. Deceased donor kidneys exposed to CS are five-fold more likely to fail than those from living donors (without CS). Thus, there is a critical need to investigate mechanisms involved with CS-induced renal injury, which will help advance the development of novel therapeutic interventions to improve transplant outcomes.
Our laboratory and others have shown that CS ‘alone’ induces renal mitochondrial dysfunction and oxidative injury. However, the extent of injury when CS is combined with transplantation (CS+Tx) as well as the identity of specific mitochondrial targets remain elusive. Exploring these questions was the primary goal of this dissertation project. First, using a novel rat renal transplant model, we demonstrated that even short-term (4h) CS exacerbates mitochondrial and renal injury after Tx compared to Tx alone (without CS). Next, we speculated that the mitochondrial large-conductance Ca2+-activated K+ channel (mitoBK) was a potential therapeutic target since its activation has been shown to be mitochondrial-protective during warm ischemic injury. The hypothesis to be tested is CS-induced mitochondrial ROS impair mitoBK channel function, which contributes to renal and mitochondrial injury. Addition of BK activators during CS protects against mitochondrial and renal injury following transplantation.
Using our rat renal cell line (NRK), we identified, for the first time, the presence of an active mitoBK channel. Cells exposed to CS followed by rewarming (CS+RW) significantly reduced mitoBK function. Excitingly, addition of the specific BK activator, NS11021 (1 μM), during CS restored mitoBK function and mitigated CS+RW-induced mitochondrial and cell injury. Finally, using our preclinical rat model of CS+Tx, NS11021 (3 μM) partially mitigated mitochondrial dysfunction and cell injury, but not renal dysfunction. Overall, these studies support our hypothesis and identify the mitoBK channel as a promising pharmacotherapeutic target for preventing CS-induced mitochondrial injury and renal injury. Future studies are warranted to better characterize mitoBK’s mitochondrial-protective role and to optimize this therapeutic approach, which is a clinically attractive strategy that avoids systemic drug exposure in the transplant recipient.
|Advisor:||MacMillan-Crow, Lee Ann, Rusch, Nancy J.|
|Commitee:||Mayeux, Philip R., Aykin-Burns, Nukhet, England, Sarah K.|
|School:||University of Arkansas for Medical Sciences|
|Department:||Interdisciplinary Biomedical Sciences|
|School Location:||United States -- Arkansas|
|Source:||DAI-B 82/4(E), Dissertation Abstracts International|
|Subjects:||Pharmacology, Cellular biology, Pathology|
|Keywords:||Cold storage, Kidney, MitoBK channel, Mitochondria, NS11021, Transplantation|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be