The kidney and the sympathetic system: a short review

Despite the well documented and very effective non pharmacologic and pharmacologic therapies, hypertension remains often poorly controlled. There is still room for improvements in blood pressure control and recent technological advances have generated a regained interest in the physiopathology of renal sympathetic innervation in hypertension. In this article we review the evidence that renal sympathetic activity is increased in essential hypertension. The postganglionic sympathetic fibers are directed to the afferent and efferent renal arterioles, the juxtaglomerular apparatus, the proximal renal tubule, the loop of Henle, as well as the distal renal tubule and are under the control of many reflex loops, which are summarized in a most comprehensive manner for an unfamiliar reader within this field of research. Studies on renal denervation have provided further insights on the role of the sympathetic system in the kidneys, however their proper interpretation requires a special attention to the experimental protocols, as is explained in the text. Last, the possibility of kidney reinnervation is discussed, as well as the emerging evidence that the kidney is also a sensory organ. In summary, this review article provides a strong scientific background to understand not only the mechanisms of the hypotensive effects, but also those of possible pitfalls, of renal denervation.