Acetylcholinesterase-Containing Nerve Fibers in the Canine Kidney

Abstract

The distribution of acetylcholinesterase in the canine kidney was studied by the histochemical method of Karnovsky and Roots and compared to the distribution of adrenergic fibers studied with the fluorescence histochemical method of Falck and Hillarp. Specific inhibitors of nonspecific cholinesterase and acetylcholinesterase were used to differentiate between the two enzymes. In the hilus, acetylcholinesterase-containing nerve fibers were found in large bundles lying adjacent to the media of the hilar arteries. In the rest of the kidney, these fibers traveled with the interlobar, arcuate, and interlobular arteries, the afferent arterioles, and the vasa recta in the outer medulla. The outermedullary nerves appeared to originate in the arcuate connective tissue sheath. Acetylcholinesterase-containing nerve fibers were not seen in association with any other structures. The distribution was similar to that of adrenergic fibers although the density of the acetylcholinesterase-containing fibers was less. Two weeks after unilateral renal denervation, no adrenergic nerve fibers could be detected histochemically in the denervated kidney, whereas acetylcholinesterase-containing nerve fibers were found in five out of seven kidneys. Acetylcholinesterase-staining ganglion cells found in the hilus of the unsuccessfully denervated kidneys appeared to be the source of the acetylcholinesterase-containing nerves. On the basis of these observations, it may be concluded that the kidney is innervated by acetylcholinesterase-containing nerves which are independent of the adrenergic nerve supply.