Differential effects of norepinephrine on brain and other less vital organs detected by a multisite multiparametric monitoring system

Background: Under emergency situations, the protection the most vital organs in the body, the brain and the heart, may result in a decrease in tissue perfusion, mitochondrial dysfunction and energetic failure, in "less-vital" organs (skin, G-I tract, kidney etc.). One of these pathways includes the secretion of epinephrine and norepinephrine. The aim of the present study was to test the effect of norepinephrine injection on the vitality of four different organs (vital and "less-vital") monitored simultaneously. Material/Methods: The four organs monitored were, the brain- a vital organ and three "less vital" organs-the kidney, liver and testis. The vitality of the organs was evaluated by monitoring the levels of microcirculatory tissue blood flow (TBF) and the level of mitochondrial NADH measured from the surface of each organ. The hemodynamic state, TBF, was monitored by the laser Doppler flowmetry (LDF) and the metabolic state was evaluated by surface fluorometry-reflectometry Results: The results indicated that following norepinephrine bolus injection the increase in mean arterial pressure (MAP) was associated with an increase in cerebral blood flow and a decrease in all three "less vital" organs TBE As a result, NADH levels in the brain remained stable whereas in all other organs NADH increased due to the hypoperfusion developed and the lack of enough oxygen in these organs. Conclusions: The significant correlation between the hemodynamic state of the organs and its mitochondrial redox state may serve as an indicator of tissue vitality under "Brain Sparing" conditions.