The BKCa-channel blocker, iberiotoxin alone or in combination with the H2O2 scavenger, polyethylene glycol catalase, reversed exercise training-enhanced dilation in collateral-dependent arterioles. Iberiotoxin-sensitive whole-cell K+ currents (i.e., BKCa-channel currents) were not different between smooth muscle cells of nonoccluded and collateral-dependent arterioles of sedentary and exercise trained groups. These data provide evidence that BKCa-channel activity contributes to exercise training-enhanced endothelium-dependent dilation in collateral-dependent coronary arterioles despite no change in smooth muscle BKCa-channel current.
Taken together, our findings suggest that a component of the bradykinin signaling pathway, which stimulates BKCa channels, is GW-572016 clinical trial enhanced by exercise training in collateral-dependent arterioles and suggest a potential role for H2O2 as the mediator. “
“To use the OZR model of the metabolic syndrome to determine the impact of dilator stimuli on MA of GA and MCA. We tested the hypothesis that increased oxidant stress and TxA2 exacerbate MA, and Selleckchem Everolimus prevent its blunting with dilator stimuli, in OZR. GA/MCA from OZR and LZR was pressurized ex vivo. MA was determined under control conditions
and following challenge with acetylcholine, hypoxia, and adenosine. Responses were also evaluated after pre-treatment with TEMPOL (antioxidant) and SQ-29548 (PGH2/TxA2 receptor antagonist). MA was increased (and dilator responses decreased) in GA/MCA from OZR, dependent on the endothelium
and ROS. In GA, the impact of ROS on MA and dilator effects was largely via TxA2, while in MCA, this appeared was more dependent on NO bioavailability. Intrinsic responses of GA/MCA to carbacyclin, U46619, and NO donors were similar between strains. A developing ROS-based endothelial dysfunction in MCA and GA of OZR contributes Megestrol Acetate to an enhanced MA of these vessels. Although treatment of GA/MCA with TEMPOL attenuates MA in OZR, the mechanistic contributors to altered MA, distal to ROS, differ between the two resistance vessels. “
“Microcirculation (2010) 17, 159–163. doi: 10.1111/j.1549-8719.2010.00028.x This edition of Microcirculation presents five current and emerging perspectives of the microcirculation in development, health, and disease. The onset of blood flow and pressure are central to cardiovascular development. These hemodynamic forces are explored in light of underlying molecular signaling pathways that affect vascular and cardiac cell shape and proliferation. Shear-induced strain exerted on the plasma membrane and cytoskeleton is transmitted to cell nuclei and thereby affects gene activation through mechanotransduction. Altered stiffness or disturbed surfaces of aberrant vascular cells may affect an array of vasculopathies through altered gene expression.