AJP - Lung Cellular and Molecular Physiology, Vol 267, Issue 6 807-L814, Copyright © 1994 by American Physiological Society
Expression of substance P and its precursor forms in vagal, tracheal, and lung tissues of the guinea pig
R. M. Kream, J. E. Marchand, S. T. O'Connor and E. I. Bloomquist
Department of Anesthesiology, Tufts University School of Medicine, Boston, Massachusetts.
Steady-state levels of the prototypic tachykinin neuropeptide substance P
(SP) and its major precursor form substance P-glycine (SP-G) were detected
and authenticated in guinea pig vagal and respiratory tissues by
radioimmunoassay (RIA), combined high-performance liquid chromatography
(HPLC)/RIA analyses, and immunohistochemistry. Four antisera were employed:
anti-SP that recognizes the amidated COOH-terminal of SP and is specific
for the mature peptide, anti-SP4-10 that recognizes the midportion 4-10
amino acid sequence of SP and is highly specific for both mature SP and
extended precursor forms of SP, anti-SP-G that is highly specific for the
unamidated COOH-terminal of SP-G, and affinity-purified anti-SP-G-K that is
capable of detecting SP-G and minor forms of SP precursor in
immunohistochemical analyses. In all examined areas, the content of
substance P4-10-like immunoreactivity (SP4-10-LI) quantified by RIA with
the use of anti-SP4-10 was greater than that quantified by RIA with the use
of anti-SP serum, thereby providing biochemical evidence of steady-state
expression of extended precursor forms of SP. Immunohistochemical analyses
demonstrated labeled axonal profiles indicating the presence of
immunoreactive SP as well as immunoreactive forms of SP precursor within
lung hilum and in small fibers in the parenchyma, with no evidence of
labeled neuronal cell bodies in these same areas.
