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