Effects of periodic axial acceleration on NO production in isolated porcine aortasin isolated porcine aortas
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abstract
Nitric Oxide (NO) is a potent regulator of vascular tone. Shear stress on the vascular endothelium is an important regulator of NO. Periodic acceleration (pGz) is a novel method of cardiopulmonary support employing a platform that moves in a headward-footward motion. PGz at frequencies between 2 to 6 Hz and accelerations Gz of 0.2 to 0.6 G, have been shown to increase vascular shear stress, increase ventilation, decrease pulmonary and systemic vascular resistances, and increase regional blood flow in pigs. The purpose of this investigation was to elucidate the mechanisms of these phenomena by determining the in vitro effects of pGz on NO production in an isolated perfused porcine aorta. Isolated perfused porcine aortas were exposed to non pulsatile (NP), pulsatile (P), and pulsatile flow plus pGz (P+pGz). A significant increase (p<0.001) in shear stress occurred from 2 4 dynes/cm2 to 67 dynes/ cm2 in the Pulsatile and Pulsatile+pGz respectively. There was also a significant increase (p<0.05) in nitrites from 0.13(0.02) vs 0.39(0.03) vs 1.37 (0.1) micromolar (mean (SEM)) for NP, P, P+pGz, respectively. PGz may ultimately be a novel method for "tuning the endothelium" in normal and diseased states.
