The kidney is the most highly innervated peripheral organ, and both the excretory and endocrine functions of the kidney are regulated by renal nerve activity. The kidney plays a dominant role in body fluid homeostasis, blood ionic concentration, and pH and thereby contributes importantly to systemic blood pressure control. Early studies suggested that the neural-renal interactions were responsible only for short-term adjustments in renal function, but more recent studies indicate that the renal nerves may be a major contributor to chronic renal defects leading to established hypertension and (or) renal disease. The neural-renal interaction is also of considerable interest as a model to elucidate the interplay between the nervous system and peripheral organs, since there is abundant anatomical and physiological information characterizing the renal nerves. The investigator has easy access to the renal nerves and the neural influence on renal function is directly quantifiable both in vivo and in vitro. In this symposium that was presented at the 1990 annual convention of the Society for Neuroscience in St. Louis, Missouri, three prominent researchers evaluate the most recent progress in understanding the interplay between the nervous system and the kidney and explore how the results of these studies relate to the broader questions concerning the nervous system's interactions.First, Luciano Barajas examines the detailed anatomy of the intrarenal distribution of the efferent and afferent renal nerves along the nephron and vasculature, and he evaluates the physiological role of each of the discrete components of the innervation. His basic science orientation combined with his deep appreciation of the clinical consequence of the failure of neural-renal regulation enhances his discussion of the anatomy. Ulla C. Kopp discusses the role of the renorenal reflex, which alters renal responses following stimulation of the contralateral kidney. She also considers her recent findings that efferent renal nerve activity can directly modify sensory feedback to the spinal cord from the kidney. Finally, J. Michael Wyss examines the functional consequences of neural control of the kidney in health and disease. Although the nervous system has often been considered as only an acute regulator of visceral function, current studies into hypertension and renal disease suggest that neural-renal dysfunction may be an important contributor to chronic diseases.Together, these presentations examine most of the recent advances in the area of neural-renal interactions and point out how these data form a basis for future research into neuronal interactions with all visceral organs. The relative simplicity of the neural-renal interaction makes this system an important model with which to elucidate all neural-peripheral and neural-neural interactions.
