Connective tissue accumulation in the left coronary artery of young SHR

The left coronary artery of 21-, 28-, and 45-day-old spontaneously hypertensive rats and Wistar-Kyoto rats was analyzed morphometrically to evaluate the structural alterations of the vessel wall during the development of genetically determined hypertension. In 45-day-old rats, hypertension was associated with a significant expansion of the partial volume of collagen and ground substance (119%) within the arterial wall. This change exceeded the concurrent accumulation of elastin (77%) and smooth muscle cell mass (34%). The growth of the muscle compartment was also characterized by a marked increment of rough endoplasmic reticulum (103%). The increase in the mural concentration of fibrous proteins at this early age may be viewed as the initial adverse effect of hypertension on muscular arteries.