Spontaneously occurring hypertrophic cardiomyopathy in the rat. I. Pathologic features

Area of Science:

• Cardiovascular Pathology
• Comparative Pathology
• Animal Models

Background:

• Cardiac hypertrophy is a significant cardiovascular condition.
• Spontaneous cardiac diseases in animal models are crucial for research.
• WKY rats are commonly used in physiological studies.

Purpose of the Study:

• To investigate spontaneous cardiac hypertrophy in WKY rats.
• To compare the cardiac pathology of WKY rats with normotensive Wistar and hypertensive SHR rats.
• To determine if the observed cardiac changes resemble human hypertrophic cardiomyopathy.

Main Methods:

• Gross anatomical and microscopic examination of rat hearts.
• Histological analysis of myocardial structure, including fiber arrangement and fibrosis.
• Electron microscopy to assess myofilament and Z-band integrity.
• Comparison of cardiac parameters between WKY, Wistar, and SHR rat strains.

Main Results:

• A substantial number of WKY rats exhibited significantly greater heart weight and ventricular septum thickness compared to Wistar and SHR rats.
• Hypertrophied WKY hearts showed abnormal myocyte hypertrophy, myocardial fibrosis, and thickened intramural arteries.
• Electron microscopy revealed myofilament disarray and widened Z-bands in hypertrophied WKY myocardium.
• Cardiac hypertrophy in WKY rats occurred without elevated blood pressure.

Conclusions:

• WKY rats spontaneously develop a myocardial disease with pathological features similar to human hypertrophic cardiomyopathy.
• This spontaneous condition in WKY rats provides a relevant animal model for studying hypertrophic cardiomyopathy.
• The findings highlight the importance of considering spontaneous pathologies in WKY rats for research accuracy.