Vasomotor responses of soleus feed arteries from sedentary and exercise-trained rats

Our goals were to determine the nature of endothelium-dependent and -indepe ndent vascular responses in isolated soleus feed arteries (SFA) and to test the hypothesis that these responses would be altered by exercise training. Exercise-trained rats ran 30 m/min, up a 15% grade, 1 h/day, 5 days/wk for 10-12 wk, while sedentary control rats were confined to normal cage activi ty. SFA were isolated, cannulated, and pressurized at 90 cmH(2)O. After a 1 -h equilibration period, the dose-response relationships to constrictors, e ndothelium-dependent dilators, and endothelium-independent dilators were ex amined. SFA developed spontaneous tone, demonstrated myogenic reactivity by maintaining vessel diameter in the face of large changes in intraluminal p ressure, and constricted in a dose-dependent manner to norepinephrine and p otassium chloride. SFA dilated in a dose-dependent manner to the endotheliu m-dependent dilators acetylcholine and increased flow and to the endotheliu min-dependent dilator sodium nitroprusside. SFA did not dilate to the putat ive endothelium-dependent dilators bradykinin, substance P, and clonidine o r to adenosine. Dilation to acetylcholine was attenuated markedly by argini ne analogs and less by 20 mM KCl, but it was unaltered by indomethacin. The se results indicate that SFA respond to a number of vasoactive substances, consistent with the hypothesis that SFA participate in the control of vascu lar resistance. However, exercise training does not appear to elicit a stim ulus adequate to alter vasomotor responses in SFA.