While bradykinin appears to be the most effective ligand for the sensory pain receptor in mammals, relatively little is known about its physiological role(s) in the more central portions of the mammalian nervous system. Bradykinin immunoreactivity is relatively prominent in hypothalamic cell bodies which project to the cingulate cortex and other regions of the brain; bradykinin receptors in dorsal root ganglion have recently been characterized in other laboratories. Strategies developed to recover milk kininogen were modified to permit solubilization and partial purification of kininogen from a bovine dorsal root ganglion tissue sample. A kinin, chromatographically identical to bradykinin, has been purified from a TPCK-trypsin digest of that tissue sample; mass spectral and chemical configurations of bradykinin are pending. Chemical characterization of pure kininogen will permit determination of whether properties of the nerve kininogen(s) are unique; such information should permit insight into strategies to modulate levels and/or effects of bradykinin in the nerve tissue.
