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KMID : 0948320060060020047
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Konyang Medical Journal
2006 Volume.6 No. 2 p.47 ~ p.52
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Effects of Aging on the Spontaneous Aortic Tone of Spontaneously Hypertensive Rats
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Kim Se-Hun
Chang Seok-Jong
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Abstract
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Effects of aging on the spontaneous tone were examined in the aorta of spontaneously hypertensive rats (SHR). The helical strip of aorta was immersed in the tris-buffered Tyrode’s solution equilibrated with 100% O2 at 35oC and its isometric tension was measured. Spontaneous tone was induced by Ca2+ addition in the Ca2+-free Tyrode’s solution. Spontaneous tone was observed in SHR but that contraction was not shown in age-matched normotensive Wistar- Kyoto rats. The spontaneous tone was greater as the SHR became older. Spontaneous tone showed dose-dependency to extracellular Ca2+ concentration and the tone reached maximum at 2~3 mM of Ca2+. Verapamil (10-6M) suppressed the spontaneous tone about 60~100%. The effect of verapamil on the spontaneous tone was greater with aging. The spontaneous tone was markedly potentiated by endothelial removal. The potentiation effect of endothelial removal was greater in young aged SHR (4, 8 week-old) than in old aged SHR (16, 24 week-old). Endothelium-dependent relaxation by acetylcholine was decreased with aging. From above results, it is suggested that degeneration of vascular function may be accelerated by aging and high blood pressure.
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KEYWORD
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Spontaneous tone, Spontaneously hypertensive rats, Aorta Aging, Endothelium
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