Intrinsic vasomotor innervation of blood vessels in human ventrolateral medulla

Medullae were obtained at autopsy from seven patients with no neurologic di sease, and sections were processed for tyrosine hydroxylase (TH), nicotinam ide adenine dinucleotide phosphate diaphorase (NADPH-d), or both. Both TH- and NADPH-d reactive neurons had close anatomical relationship with penetra ting blood vessels in the ventrolateral medulla (VLM). Three patterns were identified: 1) processes arising from a neighboring neuron reaching the blo od vessel; 2) direct appositions of cell bodies to blood vessels; and 3) fi bers coursing parallel to the blood vessels. This intrinsic innervation may provide a mechanism of coupling among local metabolism, sympathetic activi ty, and blood flow in the VLM.