Effects of renal nerves and plasma epoxyeicosatrienoic acids on blood pressure, renal hemodynamics and excretion in spontaneously hypertensive rats

Spontaneously hypertensive rats (SHR) display deficiency of epoxyeicosatrienoic acids (EETs). Their possible interaction with renal sympathetic nerves remains unexplored; synthesis of EET-A [disodium (S)-2-(13-(3-pentyl)ureido)-tridec-8(Z)-enamido)succinate], a stable 14,15-EET analog, helps clarify the issue. In anesthetized SHR, untreated or pretreated with EET-A, we assessed early responses of blood pressure (MAP), renal hemodynamics and excretion, and indices of nitric oxide (NO) activity, to bilateral noninvasive renal denervation (DNX). DNX significantly decreased MAP, with or without EET-A pretreatment. Renal perfusion decreased in EET-A treated but not in control rats. After EET-A pretreatment DNX decreased renal excretion of sodium and total solutes, compared to increasing tendency in untreated rats. In EET-A treated but not in untreated SHR denervation reduced the excretion of NO metabolites. Antihypertensive action of EET-A in anesthetized SHR was not clearly dependent on renal nerve activity. On the other hand, DNX unmasked the unexpected effect of EET-A to lower renal perfusion. The mechanism of this novel finding is unclear, as is also the simultaneous post-denervation decrease in renal excretion, again, observed only under EET-A treatment. Possibly, the decrease was secondary to falling MAP and renal perfusion. Increased renal excretion of nitric oxide metabolites under EETs elevation strongly suggests facilitation of NO release; the effect that was observed only with intact renal nerve activity.