Effect of aging on vascular smooth muscle contractility in skeletal muscle resistance arteries

Abstract

ObjectiveWe tested the hypothesis that vascular smooth muscle contractility declines with age in skeletal muscle resistance arteries.MethodsSoleus muscle feed arteries (SFA) from young (4 mo) and old (24 mo) Fischer 344 rats were cannulated with glass micropipettes and pressurized to 90 cmH2O for 1 h. To isolate the role of vascular smooth muscle, SFA were denuded (endothelium removed) by passing 5 ml of air through the lumen of the artery. At the end of the 1 h equilibration period, contractile responses were assessed using increasing whole log doses of norepinephrine (NE; 10−9–10−4 M), angiotensin II (Ang II; 10−11–10−7 M), and phenylephrine (PE; 10−9–10−4 M).ResultsVasoconstrictor responses NE, Ang II, and PE were significantly impaired in endothelium intact old SFA compared to young SFA. In contrast, vasoconstrictor responses to NE, Ang II, and PE were similar in young and old denuded SFA.ConclusionThese results indicate that the contractile properties of vascular smooth muscle cells are preserved with age and that impaired constrictor responses are manifest only when the endothelium is intact.Support or Funding InformationResearch support: AHA grant 0765043Y, AHA grant 4150031, The National Space Biomedical Research Institute through NCC 9–58 and a Sydney and J.L. Huffines Institute of Sports Medicine Graduate Student Research Grant.