Time- and order-dependent changes in functional and NO-mediated dilation during exercise training

Abstract

Arterial vessel responses to sodium nitroprusside (SNP) and acetylcholine (ACh) were measured in the spinotrapezius muscle of sedentary (Sed) and treadmill-trained (Tr) rats to determine whether these endothelium-dependent (ACh) and -independent (SNP) mechanisms contribute to the training-induced increase in functional vasodilation previously observed. Control and maximal vessel diameters were similar between Sed and Tr. After 8 wk of training, functional dilation (2-, 4-, and 8-Hz contractions) was enhanced in all orders of vessels studied [terminal feed artery (FA), largest arterioles (1A), and intermediate-sized arterioles (2A)], but responses to SNP were increased only in FA. Responses to ACh were not significantly increased in any vessel order. After 16 wk of training, functional dilation had regressed in Tr such that only the FA response to 4 Hz was significantly elevated relative to Sed. However, the FA and 1A responses to SNP were significantly greater in Tr than in Sed, as were the 1A and 2A responses to ACh. These results show a dissociation of functional dilation and SNP- or ACh-mediated responses, as well as age-dependent interactions, a time-dependent progression, and vessel order specificity in the adaptations to training.

Endurance, interval sprint, and resistance exercise training: impact on microvascular dysfunction in type 2 diabetes

“…Thus EX-induced improvements in EDD are distributed heterogeneously throughout skeletal muscle arteriolar networks, and the pattern of distribution of these effects depends on types of training and signal for EDD (i.e., ACh vs. insulin) (95,102). These observations add importantly to the growing body of evidence that highlight differences among vasomotor properties of arteries of different tissues (89), within tissue (8,41,79,89,135,136,151), and along the length of the arterial network (39,46,58,73,77,78,81,83). The relative importance of vascular control mechanisms also differs among muscles (1, 2), and endothelial phenotype varies among and within vascular beds (4,5,7,49,50,81,83,85,87,97,111,112,122).…”

“…Skeletal muscle fiber type composition and muscle fiber recruitment patterns during exercise have a major influence on vascularization, capillary exchange capacity, vascular structure, mechanisms of vasomotor control, and regional distribution of blood flow within and among muscles during exercise (10,16,63,79,87,97). Importantly, EX alters relationships among muscle fiber type, recruitment patterns, and blood flow (11,82,110,139) by modifying vascular structure, endothelium (37,38,40,71,81,85,96,98,107,120,137,142,150), and vascular smooth muscle (VSM) of skeletal muscle arteries/arterioles (77,80,81). Although many EXinduced vascular adaptations are concentrated in the muscle tissue, having the greatest relative increase in activity during training sessions (11,15,22,55,56,82,84,92,131,138,139), the relative amount of adaptation is not distributed uniformly for any of these parameters (84), and these adaptations are not the same for different types of EX (11,81,82,109,…”

Effect of a High Salt Diet on Microvascular Antioxidant Enzymes

“…In rat spinotrapezius muscle, as in many other vascular beds, endothelium-derived NO not only exerts a continuous influence on resting arteriolar tone, but also plays an important role in the active moment-to-moment regulation of blood flow [6, 28, 29, 30]. We have reported that this microvascular NO activity is lost after 2 or more weeks of high dietary salt intake [5, 6].…”

Effects of aging and exercise training on spinotrapezius muscle microvascular Po2 dynamics and vasomotor control

“…6 and 7, respectively). In the present study, endothelium-dependent vasodilation was assessed by ACh exposure, which is consistently utilized to investigate endothelial function in many vessel types (i.e., conduit through terminal arterioles) in vivo (50). Furthermore, alterations in ACh and endothelium-dependent vasodilation are strongly related to functional changes in perfusion distribution (31).…”