AJP - Heart and Circulatory Physiology, Vol 249, Issue 3 694-H697, Copyright © 1985 by American Physiological Society
High-affinity substance P binding sites in rat sympathetic ganglia
M. Niwa, K. Shigematsu, L. Plunkett and J. M. Saavedra
Substance P binding sites were characterized and quantitated in single rat
sympathetic ganglia by incubation of tissue sections with
125I-Bolton-Hunter substance P, autoradiography, image analysis coupled
with computer-assisted microdensitometry, and comparison with 125I
standards. The prevertebral celiac-superior mesenteric sympathetic ganglia
contained clusters of high-density, high-affinity substance P binding sites
[maximum binding (Bmax) 7.12 +/- 0.20 pmol/mg protein; affinity constant
(Ka) 2.08 +/- 0.02 X 10(9) M-1]. In the paravertebral superior cervical
sympathetic ganglia, the number of high-affinity substance P binding sites
was substantially lower (Bmax 1.38 +/- 0.04 pmol/mg protein; Ka 1.71 +/-
0.03 X 10(9) M-1). Future studies should address the issue of whether the
substance P binding sites identified in prevertebral ganglia of the rat
serve as receptors for the peptide presumed to be released by terminals of
sensory neurons.
