Renal Nerves and Sodium Excretion

Claude Bernard (9) in 1859 was the first to report that unilateral section of the greater splanchnic nerve in the anesthetized dog resulted in the excre­ tion by the affected kidney of an increased volume of urine with decreased chloride concentration. These changes were reversible by electrical stimula­ tion of the distal cut end of the nerve. Similar results, termed denervation diuresis and natriuresis, have been reported repeatedly since the time of Bernard. An increase in glomerular filtration rate (GFR) has often been reported following acute denervation, and the increased salt and water excretion have usually been interpreted as resulting from an increase in filtered load. The few studies in unanesthetized animals have shown little or no difference in the function of a unilaterally denervated kidney from that of the opposite and innervated control kidney. Further, the clinical experi­ ence with kidney transplantation in humans has demonstrated that a totally denervated kidney may provide adequate replacement of the individual's own kidneys. Thus the prevailing view among renal physiologists has been that the renal nerves have no important role in the regulation of renal excretory function under normal conditions. According to this view, any influences they might exert are present only under such stressful conditions as anesthesia, surgery, or trauma; they are thus in the realm of pathophysi­ ology, not physiology, and result from changes in renal hemodynamics. More recent experimental studies, reviewed here, challenge this view. The concept of a limited but important role of neural influences on renal excretory function is part of a changing concept about the functional role of the innervation of visceral organs in general. It is becoming clear that