Hyaluronan is differently located in arteries and veins. An immunohistochemical study in the rat

The matrix components of the vessel wall are of great importance for the function of the vessel system of which both endurance and elasticity are prerequisites. One component of the vessel wall is the glycosaminoglycan hyaluronan (HYA) with its unique physico-chemical properties, e.g. viscoelasticity and barrier function. The present study aimed to map and compare the normal localisation and distribution of hyaluronan in the arteries and veins of both adult and newborn rats, using a specific staining method utilizing a hyaluronan-binding protein. The hyaluronan stained clearly different in veins and arteries both in newborn and adult rats. In the veins, the tunica intima stained intensely whereas the corresponding area in the arteries only showed a weak and scattered staining pattern. In the adult rats, the matrix between the smooth muscle cells of the tunica media of the veins had a clearly positive staining pattern compared to the media in the arteries which showed only a few scattered areas of positive staining. In the newborn rats, the media of the arteries stained more intensely. In both newborn and adult rats, the adventitia stained intensely both in veins and arteries. Moreover, the HYA-staining pattern differed in veins in different regions of the body. Since HYA is known to be involved in many different biological processes, the results are of importance to understand physiological properties of the vessel tree and to explain the development of vascular diseases.