Extracellular matrix maturation in the left ventricle of normal and diabetic swine.

The main objective of this study is to determine the transmural distribution of extracellular matrix (ECM) collagen and maturation in non-diabetic and diabetic hearts. The Yucatan miniature swine heart ECM was analyzed in eight streptozotocin (STZ) induced diabetic pigs (Diabetic-Swine) and age matched normal control pigs (Nondiabetic-Swine). After 12 weeks of STZ induced diabetes, transmural biopsies were obtained from the left ventricular free wall divided into subendocardial, mid- and subepicardial layers. Collagen concentration and maturation were measured by RP-HPLC determination of hydroxyproline (Hyp) and content of hydroxylysylpyridinoline (HP) cross-links, respectively. Results showed a significant elevation in arterial glucose (P<0.05) and reduction in arterial plasma insulin levels in the Diabetic-Swine. Hyp concentration was significantly greater (P<0.05) in the subendocardial layers in both the Diabetic and Nondiabetic animals. The HP cross-link content was significantly greater (17%) in the Diabetic-swine subendocardial layer compared to Nondiabetic-Swine (P<0.05), but not in other layers. In summary, the accumulation and/or increase in HP cross-link content in the Diabetic-Swine subendocardial layer suggests that myocardial fibrosis may be greater in this specific region.