Effect of Aging on Vascular Smooth Muscle Myogenic Contractility in Soleus Muscle Feed Arteries
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ObjectiveWe tested the hypothesis that vascular smooth muscle (VSM) myogenic constrictor responses decline with age in soleus muscle feed arteries (SFA). In addition, we asked whether pretreatment of SFA with a short duration (1 h) increase in intraluminal pressure, to mimic pressure associated with a bout of exercise, would have beneficial effects on myogenic responses in SFA.MethodsSFA from young (4 mo) and old (24 mo) Fischer 344 rats were cannulated with glass micropipettes and endothelial cells were removed (denuded) by passing 5 ml of air through the lumen of the vessel. SFA were then pressurized to 90 cmH2O (p90) or 130 cmH2O (p130) for 1 h. At the end of the 1 h treatment, intraluminal pressure in all arteries was set to 90 cmH2O for examination of VSM myogenic constrictor function. After stable tone was achieved, myogenic contractile responses were assessed using stepincreases in intraluminal pressure from 90 cmH2O to 135 cmH2O in 15 cmH2O increments followed by stepdecreases down to 45 cmH2O.ResultsMyogenic responses of denuded old SFA (p90) was not different from denuded young SFA (p90). Pretreatment of SFA with increased pressure for 1 h improved myogenic constriction in young SFA (p130) but not in old (p130).ConclusionVSM myogenic responses were not altered with age in denuded SFA. Pressure treatment contributed to enhanced myogenic constrictor responses in young SFA.Support or Funding InformationNIH grant R03AG064551, Sydney and J.L. Huffines Institute of Sports Medicine and Human Performance, and CEHD Research Fellowship, Texas A&M University
