Adrenergic Innervation of the Canine Kidney

The adrenergic innervation of the canine kidney was studied with the fluorescence histochemical method of Falck and Hillarp in conjunction with chemical assays for catecholamines in specific portions of the kidney. Adrenergic nerve fibers were seen traveling along the interlobar, arcuate, and interlobular arteries and along the afferent arterioles. The vasa recta of the outer medulla also received adrenergic innervation. Adrenergic nerve fibers were never seen in association with the glomerulus, the efferent arteriole, or the tubules. The distribution of the nerve fibers agreed with the distribution of norepinephrine. After administration of reserpine or denervation of the kidney, no adrenergic nerve fibers were seen, and the norepinephrine level in all portions of the kidney fell to negligible levels. Accumulation of norepinephrine in the nerve fibers was observed after kidney slices had been exposed to solutions of norepinephrine. On the basis of these experiments, it was concluded that the fibers visualized with the fluorescence histochemical method were adrenergic nerve fibers. The possible physiologic role of the adrenergic innervation of the canine kidney is discussed.