Journals of Gerontology Series A: Biological Sciences and Medical Sciences Large Type Edition
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Articles by McDonald, A.
Articles by Howie, K. A.

Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 50, Issue 1 B20-B25, Copyright © 1995 by The Gerontological Society of America


JOURNAL ARTICLE

No evidence for a general change in contractile responsiveness of the mesenteric artery with aging

A McDonald, E MacDonald, JD Fulton, RM Wadsworth, PJ Scott and KA Howie
Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, Scotland.

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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