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  • Title: No evidence for a general change in contractile responsiveness of the mesenteric artery with aging.
    Author: McDonald A, MacDonald E, Fulton JD, Wadsworth RM, Scott PJ, Howie KA.
    Journal: J Gerontol A Biol Sci Med Sci; 1995 Jan; 50A(1):B20-5. PubMed ID: 7814775.
    Abstract:
    Rings of human mesenteric artery (1-3 mm diameter) suspended in Krebs solution were contracted (maximal contraction relative to KCl 80 mM = 100%) by the thromboxane mimetic U46619 (190 +/- 10%), noradrenaline (162 +/- 9%), angiotensin II (107 +/- 11%), and 5-hydroxytryptamine (5-HT) (96 +/- 10%). Reducing extracellular Ca2+ strongly inhibited the maximal contraction to angiotensin II and 5-HT and moderately inhibited the maximal contraction to noradrenaline, but had less effect on the maximal contraction to U46619 (contraction in Ca2+ 1.3 microM was reduced to 24 +/- 5, 20 +/- 3, 38 +/- 4 and 52 +/- 4% respectively of the contraction in 2.5 mM Ca2+). Reducing extracellular Ca2+ lowered sensitivity to 5HT, angiotensin II, and U46619, but did not alter sensitivity to noradrenaline. The EC50 and maximal contraction for each of the 4 agonists did not change with patient age at 2.5 mM Ca2+ or in reduced extracellular Ca2+. It is concluded that aging does not affect the responsiveness of mesenteric arterial smooth muscle to physiological vasoconstrictors.
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