C natriuretic peptide is found in:

A third member of this family has been named C-type natriuretic peptide (CNP) because it was the third in the sequence to be isolated. It contains 22 amino acid residues, and there is also a larger 53-amino-acid form. CNP is present in the brain, the pituitary, the kidneys, and vascular endothelial cells. However, very little is present in the hea and the circulation, and it appears to be primarily a paracrine mediator. Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 39.