Local Forearm Heating Does Not Alter Concentrations of Circulating Notch1 ECD and HSPG/CD44
Abstract
Endothelial dysfunction underlies the pathophysiology of cardiovascular disease. While advances have been made for treatment and management, many gaps in knowledge remain. Recently, heat therapy has gained attention for improving vascular endothelial function, tenably through increases in antegrade shear stress (SS). However, no study has examined the molecular mechanisms associated with SS and heating. Accordingly, the aim of this study was to determine how local forearm heating may impact Notch1 and Heparan Sulfate Proteoglycan (HSPG), which are transmembrane endothelial mechanosensors essential for preserving endothelial integrity and signalling. We hypothesized that 40-minutes of increased antegrade SS from forearm heating will increase the concentration of circulating Notch1 and HSPG/CD44. 9 healthy young adults underwent forearm heating by immersion in 42°C water for 40 minutes. Venous blood samples of the heated forearm were taken prior to and during heating. Concentrations of plasma Notch1 and HSPG/CD44 were subsequently determined by ELISA. Duplex ultrasound was used to determine SS in the brachial artery. Results: Antegrade SS was increased by heating (P<0.01), however, the concentrations of Notch1 and HSPG/CD44 did not change throughout the heating protocol compared to baseline (P both >0.05). These data indicate that the SS from forearm heating is not sufficient to increase Notch1 and HSPG/CD44, suggesting that the benefits of heating may not arise from the increases in antegrade SS, at least when quantified from circulating changes in Notch1 and HSPG/CD44, or local forearm heating is an insufficient stimulus to be used as heat therapy.