Autonomic innervation of the periglomerular arteries

To explore spatial and volume relations of the calcitonine gene-related peptide (CGRP)-positive and tyrosine hydroxylase (TH)-positive nerve fibers in the wall of cortical blood vessels.

Kidney specimens from 10 rats were processed for confocal microscopy. Nerve fibers were stained with anti-CGRP and anti-TH antibodies and image stacks were collected. Three-dimensional reconstruction and quantification of labeled fibers were performed to reveal their distribution and spatial relations.

CGRP- and TH-immunoreactive nerve fibers were distributed throughout the kidney cortex. TH-positive fibers were dominant in the small periglomerular arteries (up to 4.6-fold). Examined nerves were finely intertwined in the wall of small blood vessels of the kidney and ran in the same nerve bundle but without co-localization. Extensive, web-like branching and varicosities of the TH nerves were observed. Sensory fibers prevailed in the wall of the larger arteries "embedded" into tubules near the medullary rays, and their endings can be verified in the muscularis layer of the interlobular arteries.

Characteristics of the investigated fibers emphasize their role in the regulation of kidney blood vessel diameter and their influence on hypertension onset.