Role of nitric oxide in vasodilation in upstream muscle during intermittent pneumatic compression

Abstract

This study investigated the dosage effects of nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on intermittent pneumatic compression (IPC)-induced vasodilation in uncompressed upstream muscle and the effects of IPC on endothelial NOS (eNOS) expression in upstream muscle. After L-NMMA infusion, mean arterial pressure increased by 5% from baseline (99.5 +/- 18.7 mmHg; P < 0.05). Heart rate and respiratory rate were not significantly affected. One-hour IPC application on legs induced a 10% dilation from baseline in 10- to 20-microm arterioles and a 10-20% dilation in 21- to 40 microm arterioles and 41- to 70-microm arteries in uncompressed cremaster muscle. IPC-induced vasodilation was dose dependently reduced, abolished, or even reversed by concurrently infused L-NMMA. Moreover, expression of eNOS mRNA in uncompressed cremaster muscle was upregulated to 2 and 2.5 times normal at the end of 1- and 5-h IPC on legs, respectively, and the expression of eNOS protein was upregulated to 1.8 times normal. These increases returned to baseline level after cessation of IPC. The results suggest that eNOS plays an important role in regulating the microcirculation in upstream muscle during IPC.

External mechanical compression reduces regional arterial stiffness

“…External mechanical compression has been shown to augment arterial flow regulation in upper and lower limbs (Bochmann et al 2005;Kirby et al 2005;Morris and Woodcock 2004;Tschakovsky et al 1996) and elicit significant vasodilation (Chen et al 2002;Clifford et al 2006). Present findings extend previous findings by demonstrating that external mechanical compression also reduces pulse wave velocity of the region compressed, suggesting a reduction in local artery stiffness.…”

“…This compression-related hyperemia may be related to local vasodilation of feed arteries (Chen et al 2002;Clifford et al 2006) in concert with venous emptying related to fall in capacitance vessel pressure during relaxation (i.e., muscle pump) (Tschakovsky et al 1996). Conditions that elicit smooth muscle relaxation are associated with concomitant reductions in arterial stiffness (Lemogoum et al 2004;Schmitt et al 2005).…”

Intermittent pneumatic leg compressions acutely upregulate VEGF and MCP-1 expression in skeletal muscle

“…The lack of change in eNOS mRNA expression is at odds with the results of previous investigations that employed a rat model of IPC (6,44). Tan et al (44) reported that application of compressions rapidly increased eNOS mRNA by up to 180% in the rat TA.…”

Peripheral conduit and resistance artery function are improved following a single, 1-h bout of peristaltic pulse external pneumatic compression

“…Although IPC application methods vary amongst studies in the literature, IPC has demonstrated some promise with regard to acute effects on vascular function. Indeed, in a rodent model, endothelial nitric oxide synthase (eNOS) mRNA expression and protein concentration have been shown to be significantly upregulated 4-h following a 1-h bout of IPC (Chen et al 2002;Tan et al 2006). However, in human application, although local hemodynamic shear stress is significantly increased during treatment, FMD and peak reactive hyperemic blood flow in the resistance arteries do not appear to be immediately improved following acute and chronic IPC application, respectively (Roseguini et al 2010;Sheldon et al 2012).…”