Adaptation of chronic renal microdialysis to evaluate the role of interstitial ATP and angiotensin II in accelerating nephropathy and oxidative stress during insulin induced hypertension (1088.3)

Various studies demonstrated the role of ATP in regulating hemodynamic functions and play a key role in maintaining tubuloglomerularfeedback (TGF) and renal vascular resistance. Previous studies also demonstrated the role of Ang II and HO‐1 in regulating blood pressure. We thus hypothesize that insulin induced hypoglycemia augments interstitial ATP levels which in turn increases AngII. This stimulates afferent arteriolar vasoconstriction interrupting normal TGF mechanism resulting in hypertension leading to oxidative stress and ultimately renal damage. Male Sprague Dawley rats (200‐225g) were anesthetized and microdialysis probe was inserted into their renal cortex. Post surgery rats were treated with insulin (7U/kg body weight) or vehicle for 2 weeks. Dialysate was collected daily after insulin dosing and analyzed for ATP by luciferin‐luciferase assay and Ang II by ELISA. ATP levels were elevated from 4.75 ng (day 0) to 36.47 ng (day 14). Heart and kidneys were collected at the end and analyzed for oxidative stress using EPR (Electron Paramagnetic Resonance). Oxidative stress was observed from the spectra obtained by using spin probes CMH and CPH. Thus the present study demonstrates a correlation between interstitial ATP and oxidative stress by real‐time chronic collection of renal interstitial samples, demonstrating the ability of hypoglycemia to promote the development of hypertension in turn accelerating oxidative stress. Grant Funding Source : Board of Regents Research Competitiveness 2010