MORPHOMETRIC ANALYSIS OF HYPERTENSION-INDUCED HYPERTROPHY OF RAT THORACIC AORTA

  • 1 January 1977
    • journal article
    • research article
    • Vol. 88  (3) , 619-633
Abstract
The response of the intima-media of the thoracic aorta to 1-4 wk of 2-kidney renal hypertension in the rat was analyzed by morphometric techniques at light and EM levels. The increased thickness of the aorta that ensues is the result of an increase in the size but not the number of smooth muscle cell layers. The volume fractions of intima occupied by endothelium (26%), internal elastic lamina (37%), and subendothelial space (37%) in normotensive animals are not significantly altered by the hypertension. The percent increase in muscle cross-sectional area is greatest (58-60%) in the 2 innermost layers (M1 and M2). M1 is composed of nearly equal compartments of smooth muscle cells and interstitial space that expand 69% and 50%, respectively, with hypertension. Analysis of the subcellular constituents of the M1 smooth muscle cells indicates that significant changes in absolute volume include increases of caveolae (45%), myofibrils (59%), mitochondria (81%), glycogen (163%), and rough endoplasmic reticulum (221%). Factors contributing to these alterations are discussed.