ROLE OF RENAL NERVES FOR THE EXPRESSION OF RENIN IN ADULT-RAT KIDNEY

Utilizing a combination of mechanical and chemical unilateral denervat ion, we have examined the relevance of renal innervation for the expre ssion of renin in kidneys of adult rats. Renal denervation led to a re duction by 57 +/- 4% of renin-containing areas in denervated kidneys a s quantitated by morphometry of kidney sections immunoreactive against a polyclonal antirenin antibody. Preprorenin mRNA content in the dene rvated kidneys fell to 46 +/- 7% of the contralateral innervated kidne ys. Treatment of rats with the beta(1)-adrenoreceptor antagonist metop rolol (100 mg. kg(-1). day(-1)) for 2 days decreased renal renin mRNA levels to 71% of control levels. Unilateral renal denervation led to a further decrease of renin mRNA levels also in metoprolol-treated anim als to 60% of the values found in the contralateral kidneys. Hypotensi ve hemorrhage led to a 1.4-fold increase of renin mRNA in the kidneys of sham-treated animals. In unilaterally denervated rats renin mRNA in creased to levels similar to those in sham-operated animals in both de nervated and in contralateral innervated kidneys in response to bleedi ng. As a consequence, the ratio of abundance of renin mRNA in the dene rvated to the innervated kidneys rose to 86 +/- 7%. Pretreatment of th e animals with metoprolol, on the other hand, prevented the rise of re nin mRNA in response to hypotensive hemorrhage. Our findings suggest t hat in the adult organism renal neural input significantly contributes to the expression of renin under basal conditions, while it appears t o be of less importance for stimulation of renin gene expression by se vere blood loss.