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KMID : 0377519910160040509
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Chung-Ang Journal of Medicine
1991 Volume.16 No. 4 p.509 ~ p.523
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Ultrastructural Study on the Changes of the Myocardium
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Abstract
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Left ventricular hypertrophy is a common sequence as the process of adaptive structural changes in arterial hypertension.
Considerable attention has been devoted in recent years to the hemodynamic and nonhemodynamic factors such as sympathetic nervous system, intracellular renin-angiotensin system and genetic influence with intraceIluar signals to hypertrophy.
The spontaneously hypertensive rat(SHR) is generally held to be a reliable model and experimental counterpart for the essential hypertension in man. In this particular strain of rat, severe and sustained systemic hypertension invariably occurs, accompanied by marked cardiac hypertrophy and interstitial proliferation.
The blood pressure of SHR, rised gradually from the 5th week after birth and reached nearly 190 mmHg, at the 16th week. Hypertension (systolic BP>140mmHg) developed in 20% of SHR at the age of 7 weeks, in 72% of SHR at the age of 10 weeks and in 100% of SHR at the age; of 16 weeks. The ratio of heart weight to body weight was significantly higher in SHR than Wistar rats. The significant increase in myofibril/mitochondria volume ratio in SHR suggests a decreased ratio of energy-producing volume to energy-consuming volume and also indicates a disproportionate synthesis of these organelles´ during hypertrophy.
There were marked changes in the intercalated discs associated with numerous immature sarcomeres. Intercalated discs were increased in number as well as height of undulations in the myocardium of SHR. Focal accumulation of mitochondria in the subsarcolemmal region was also commonly noted in SHR.
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