Role of the renal nerves in the control of renin synthesis during different sodium intakes in the rat

Objective The aim of this study was to evaluate the role of the renal nerve s in the regulation of renin synthesis in normotensive rats at different so dium balance. Methods Forty-eight male Sprague-Dawley rats were divided in six experiment al groups, combining three diets at different NaCl content (normal 0.4%, lo w 0.04% or high 4.0%), and the surgical, bilateral renal denervation or the sham procedure. After 7 days of dietary treatment, all rats were sacrifice d and plasma renin activity (PRA) was measured, Renin messenger RNA (mRNA) levels in the renal cortex were determined by semiquantitative polymerase c hain reaction, Results PRA was higher in animals fed the low sodium diet compared with tho se at standard diet, while it was lower in animals fed the high sodium diet . Renal denervation decreased PRA in normal and low sodium groups, while it did not alter the PRA values in the high sodium group. Renin gene expressi on significantly increased in rats fed with the low sodium diet compared wi th the standard diet group, and significantly decreased in rats fed the hig h sodium diet. Renal denervation significantly reduced renin mRNA levels in rats receiving the low sodium diet, but did not produce any significant ch ange in normal or high-sodium groups. Conclusion The activation of renin gene expression during sodium depletion in rats is dependent on the presence of the renal nerves, while the suppres sion of renin gene expression during a sodium load seems to be due to the m acula densa mechanism alone. (C) 2001 Lippincott Williams & Wilkins.