The Role of Protein Kinase C Epsilon in the Regulation of Endothelial Nitric Oxide Synthase (eNOS) during Oxidative Stress caused by Extracorporeal Shock Wave Lithotripsy (ESWL)

BACKGROUND: Clinical ESWL treatment to ablate kidney stones can cause acute to chronic damage in renal microvasculature leading to decreased renal blood flow and hypertension. Shockwaves can stimulate endothelial cells to release superoxide resulting in decreased nitric oxide (NO) bioavailability and increased oxidative stress, causing vascular endothelial dysfunction in the kidney. When the dihydrobiopterin:tetrahydrobiopterin ratio is increased during oxidative stress such as ESWL, eNOS becomes uncoupled and produces superoxide instead of NO. Superoxide is converted to hydrogen peroxide (H2O2) by superoxide dismutase. Protein kinase C epsilon (PKC-ε) is known to positively regulate endothelial NO synthase (eNOS) activity. In order to establish controls for the effects of PKC-ε activator and inhibitor, the effect of ESWL was tested by the comparison of ESWL-treated rats to those with no ESWL exposure, both with a saline infusion. We hypothesized that the PKC-ε peptide inhibitor (Myr-EAVSLKPT, MW = 1054.6) would decrease ESWL-induced H2O2 release and decreased the attenuation of NO release compared to ESWL-saline control rats. PKC-ε activator (Myr-NDAPIGYD, MW = 1098.5) was expected to show no effect on H2O2 or NO release, displaying a similar trend to ESWL-saline control rats