Influence of renal nerves on renal function during development.

The present review summarizes recent studies describing the role of renal sympathetic innervation in the regulation of renal function during development. The afferent renal innervation appears early during fetal life and probably precedes the development of efferent renal nerves. There is suggestive evidence that renal nerves are required for the proper development of the kidney and that neurotrophic growth factors play an important role in renal embryogenesis and in renal tubular differentiation. Renal sympathetic innervation modulates renal hemodynamics early during development. Renal nerve stimulation during alpha-adrenoceptor blockade produces renal vasodilation in fetal and newborn animals but not in adults. Unlike the effect of renal nerves on fetal renal hemodynamics which is observed in the young fetus, the role of renal sympathetic nerves in modulating fluid and electrolyte homeostasis seems to develop during late gestation. Recent studies have also shown that renal nerves play an important role in regulating renin secretion during the transition from fetal to newborn life. For example, renal denervation during fetal life suppressed the physiological rise in plasma renin activity associated with delivery and decreased renal renin mRNA levels after birth. Taken together, these studies suggest that renal nerves influence fetal renal development and that the influence of renal sympathetic innervation on renal hemodynamics and function changes with maturation.