Date of Award

4-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program

Biomedical Sciences

Track

Cell Biology and Physiology

Research Advisor

Adebowale Adebiyi, PhD

Committee

Zheng Fan, PhD; Kafait Malik, PhD; Frank Park, PhD; Kaushik Parthasarathi, PhD; Valeria Vasquez, PhD

Keywords

Acute kidney injury, Endothelin-1, Myoglobin, Renal vasoregulation, Rhabdomyolysis, TRPC3

Abstract

In patients with rhabdomyolysis, the overwhelming release of myoglobin into circulation is the primary cause of kidney injury. Myoglobin causes direct kidney injury as well as severe renal vasoconstriction. An increase in renal vascular resistance (RVR) results in renal blood flow (RBF) and glomerular filtration rate (GFR) reduction, tubular injury, and acute kidney injury (AKI). The mechanisms that underlie rhabdomyolysis-induced AKI are not fully understood but may involve the local production of vasoactive mediators in the kidney. Myoglobin stimulated endothelin-1 (ET-1) production in proximal tubular cells, an effect driven by NADPH oxidase-dependent oxyradical generation. Rats subjected to glycerol-induced rhabdomyolysis also exhibited ROS-dependent ET-1 production. Vasoactive ET-1 is generated by ET converting enzyme 1 (ECE-1)-induced proteolytic processing of inactive big ET to biologically active peptides. The downstream ion channel effectors of ET-1-induced vasoconstriction are smooth muscle Ca2+ permeable transient receptor potential canonical (TRPC) channels. TRPC1, 3, 4, 5, and 6 are expressed in renal vessels, with TRPC3 predominant. TRPC3, TRPC6, and TRPC7 are highly homologous. Although the ET system is known to be associated with rhabdomyolysis-induced AKI, the function of renal vascular ion channels in the disease was unclear. Our findings demonstrate that glycerol-induced rhabdomyolysis in Wistar rats promotes ECE-1-dependent ET-1 production, RVR increase, GFR decrease, and AKI. Rhabdomyolysis-induced increases in RVR and AKI in the rats were attenuated by post-injury inhibition of ECE-1, ET receptors, and TRPC3 channels. We used TRPC3 and TRPC6 knockout (KO) rats to support the pharmacological approaches. Basal day and night arterial pressure, heart rate, GFR, plasma creatinine, and BUN were unchanged in WT vs. KO rats. Twenty-four h rhabdomyolysis led to comparable increases in urinary ET-1 production in WT and KO rats. CRISPR/Cas9-mediated knockout of TRPC3-, but not TRPC6 channels attenuated rhabdomyolysis-induced decreases in GFR, elevations in BUN, and plasma creatinine. Similarly, morphological kidney damage (tubular necrosis, casts, and dilatation) was mitigated in the TRPC3 KO with no protection offered by the KO of TRPC6 channels. Together, our data suggest that myoglobin-driven ET-1 production and downstream activation of TRPC3- but not TRPC6-dependent vasoconstriction contributes to rhabdomyolysis-induced AKI. Hence, postinjury inhibition of ET-1-mediated renal vasoregulation may provide therapeutic targets for rhabdomyolysis-induced AKI.

Declaration of Authorship

Declaration of Authorship is included in the supplemental files.

ORCID

https://orcid.org/0000-0002-8935-5603

DOI

10.21007/etd.cghs.2023.0622

Additional Files
2023-009-Afolabi-DOA.pdf (194 kB)
Declaration of Authorship
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Available for download on Monday, April 28, 2025

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