Hypertension in Weanling Rabbits
At birth, the blood pressure in the rabbit is around 35–40 mm Hg. and the cardiovascular system is quite immature. Over the next 10–12 weeks, blood pressure rises progressively to reach the adult levels of 90–100 mm Hg.
Experimental renal hypertension has been induced in N.Z. White rabbits aged 4–6 weeks, by wrapping one or both kidneys in cellophane. Sham operated animals served as controls. The aortas were removed at 6–14 weeks after operation and collagen and elastin contents determined. Elastin was determined gravimetrically in its alkali-insoluble form.
It was found that the collagen and elastin contents (expressed as percentages of the dry defatted wall mass), of aortic segments from the hypertensive animals did not differ significantly from those 1n sham-operated control groups. However, the aorta mass of the hypertensive animals was almost twice that of the controls. Thus the absolute amounts of collagen and elastin had significantly increased in response to hypertension.
The results indicate that hypertension, induced during the rapid growth phase, causes major changes in elastin and collagen synthesis and/or remodeling and that these changes vary with location in the aorta so that they maintain the nonuniform pattern of collagen and elastin distribution typical of this species.
KeywordsAbdominal Aorta Thoracic Aorta Severe Hypertension Renal Hypertension Hypertensive Animal
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