Hunt 2018 J Urol
|Marked increase in mitochondrial respiration, hydrogen peroxide emitting potential and ATP production in the urothelium versus detrusor smooth muscle.|
Link: Open Access
Event: The Journal of Urology
The bladder urothelium and detrusor smooth muscle both play important distinct roles in voiding. Many studies have shown that the urothelium can release both luminal and apical ATP in response to stimulation and ATP release is enhanced under diseased states. ATP is primarily produced by the electron transport chain within the mitochondria. The mitochondria are also responsible for regulating cellular metabolism and homeostasis. This study aims to characterize mitochondrial function in the urothelium and detrusor smooth muscle under normal physiological conditions.
Bladders were excised from adult male C57BL/6N mice (16wks, n=10), cut open longitudinally and the urothelium layer was carefully removed as a whole sheet. The urothelium and detrusor were subdivided into smaller pieces and places in the Oroboros Oxygraph- 2K. High-resolution respirometry measured mitochondrial oxygen consumption at complexes I, II, and IV in isolated urothelium and detrusor samples. Mitochondrial derived hydrogen peroxide (H2O2) emission was also measured. Simultaneous measurement of mitochondrial respiration and ATP production was assessed in both tissues to determine the phosphate to oxygen (P:O) ratio, a measure of ATP production. Mitochondrial content was measured via citrate synthase assay and OXPHOS protein expression.
Mitochondrial oxygen consumption rates in the bladder was doubled in the urothelium at complex I, complex IV, and complexes I+II compared to the detrusor smooth muscle (p<0.05). Additionally, the urothelium was able to emit significantly greater amounts of H2O2 (p<0.05). The P:O ratio was also doubled int he urothelium indicating that it has a greater ability to generate ATP. Citrate synthase activity was unchanged between the detrusor and urothelium indicating that the amount of mitochondria is similar between groups.
This study is the first to examine mitochondrial respiration in intact urothelium and detrusor smooth muscle. The urothelium has greater rates of mitochondrial respiration, H2O2 emission potential and ATP production compared to the detrusor smooth muscle. Interestingly there was no change in citrate synthase activity indicating that there are distinct differences in mitochondrial function between these two tissue types within the bladder.
Labels: MiParea: Respiration
Organism: Mouse Tissue;cell: Endothelial;epithelial;mesothelial cell Preparation: Intact cells
Pathway: N, S, CIV, NS HRR: Oxygraph-2k