Proteoglycans and hypertension. I. A biochemical and ultrastructural study of aorta glycosaminoglycans in spontaneously hypertensive rats.

The extracellular matrix of blood vessel walls contains elastin, collagen, and proteoglycans, all of which can affect vascular resistance and, hence, blood pressure by virtue of their biomechanical properties. In the present study, we have begun to explore the possibility that proteoglycans may play a role in the pathophysiology of hypertension by analyzing, qualitatively and quantitatively, the polysaccharide components of proteoglycans from aorta of two normotensive rat strains, Wistar Kyoto (WKY) and Wistar rats, and from spontaneously hypertensive (SH) rats of the Okamoto strain. The total concentration of aorta glycosaminoglycans in the SH rat was 33% higher than in the WKY rat, due to a 164% increase in chondroitin 4- and 6-sulfate. The content of dermatan sulfate (DS), hyaluronic acid (HA), and heparan sulfate (HS) was similar in the two strains. The 4-wk-old SH rat also had an increase in chondroitin sulfate (CS) compared to the 4-wk-old WKY rat, without any change in DS, HA, or HS. The Wistar rat had approximately the same concentration of CS und DS in the aorta as the WKY rat, but HS und HA were reduced by 62 and 37%, respectively. The galactosaminoglycans (CS and DS) were heterogeneous on cellulose acetate electrophoresis and exhibited a different pattern for each of the three strains. Undersulfated CS accounted for 15% of the total CS in WKY aorta but was present in only trace amounts in the SH aorta; 2% of the CS from the Wistar aorta was undersulfated. In all three strains, DS was exclusively 4-sulfated, and the CS contained approximately equal amounts of 4- and 6-sulfated galactosamine residues. Ultrastructural studies demonstrated that the HS was localized in the subendothelial matrix and the pericellular region surrounding the medial smooth muscle cells. CS and DS were primarily associated with collagen in the media. In the SH rat aorta the subendothelial matrix was thicker, and there was a relative increase in the CS/DS in the smooth muscle cell pericellular matrix. We suggest that, if similar alterations in CS proteoglycans are present in the resistance vessels, these changes may contribute to the increased peripheral vascular resistance in the hypertensive animal.