(1) Development of survey methods for new vasoactive peptides : In addition to our previous methods using contractile or relaxant activity on several smooth muscle preparations, We developed a new method measuring second messengers in the cell, such as cAMP and cGMP, in cultured vascular smooth muscle cells and endothelial cells.
(2) production of CNP in THP-1 cell line : We detected strong chick rectum relaxant activity in phorbol-ester (TPA) supplemented culture medium of monocytic leukemia cell line, THP-1. From the culture medium, we purified a peptide exhibiting rectum relaxant activity. The peptide was determined to be CNP-29 by structural analyses.
Since vascular smooth muscle cells (VSMC) express CNP-specific GC-B receptor, CNP derived from monocytes (or macrophages) may regulate VSMC functions.
(3) C-type natriuretic peptide (CNP) : CNP has been recognized as a neuropeptide functioning in the central nervous system. By using the PCR method and highly sensitive RIA method, we found CNP and its mRNA in the peripheral tissue, including aorta, kidney, lung, gastrointestinal tract. These results suggest that CNP may be a local regulator functioning through paracrine mode.