ABSTRACT
Substance P is a potent vasodilator, and provides a rational explanation to the well-known phenomenon of antidromic vasodilatation, as well as increased vascular permeability during the so-called ‘‘triple response”. Calcitonin Gene-Related Peptide (CGRP) coexists with substance P in small-diameter primary sensory neurons, it has strong dilatory effects in its own right and potentiates the effect of substance P both quantitatively and temporally. There is reason to believe that substance P, and probably also CGRP, play a widespread role in cardiovascular control, besides its associated involvement in certain sensory functions. Substance P belongs to a group of polypeptides known as tachykinins. The immunohistochemical localization of substance P in defined groups of small-diameter cell bodies in the spinal ganglia as well as in nerve fibers in the periphery and in the dorsal horn of the spinal cord forms the neurochemical basis for the role of the peptide in nociceptive function.
