Effects of high-cholesterol diet on the interendothelial clefts and the associated junctional complexes in rat aorta

The arterial endothelial intercellular cleft (AEC) and its associated junctional complex (JC) are the determinants of permeability to macromolecules. This study analyzed frequencies of AEC and JC profile types in the rat thoracic aorta at 1 and 12 months after feeding the animals with a normal or a high-cholesterol diet. Rats on either a normal diet or high-cholesterol diet for 12 months showed more of the simple ‘end to end’ or ‘overlap’ types (P<0.01) but fewer complex ‘interdigitating’ type (P<0.01) of AEC compared to the 1 month group. With regard to JC, the frequencies of gap junctions were decreased (P<0.01) while the tight junctions and the normal junctionless complex were increased (P<0.01) after 12 months of normal diet as compared with 1 month on the normal diet. These changes in frequencies for gap junction and tight junction were even greater for the high-cholesterol diet than for the normal diet treatment. Moreover, the incidence of open junctions was also noticeably increased after 12 months of high-cholesterol diet. These findings suggest that the proportions of the AEC and JC were highly responsive to aging whereas those of JC were more susceptible to the high-cholesterol diet treatment.