C Wittnich1, S M Torrance, C E Carlyle. 1. Institute of Medical Science, University of Toronto and Division of Cardiovascular Surgery, The Hospital For Sick Children, Ontario, Canada. c.wittnich@utoronto.ca
Abstract
BACKGROUND: This study examines the effect of neonatal exposure to clinically relevant hyperoxia levels on both in vivo myocardial metabolism and the subsequent metabolic response to global ischemia. METHODS: Three-day-old pigs were ventilated to normoxia (80 mm Hg, 2 or 5 hours, n = 11), mild hyperoxia (250 mm Hg, 2 hours, n = 9), or severe hyperoxia (500 mm Hg, 5 hours, n = 14). Ventricular biopsies obtained at the end of the ventilation period, and at early and late ischemia were analyzed for ATP, ADP, AMP, creatine phosphate, glycogen, and lactate. RESULTS: Hyperoxia did not significantly alter in vivo metabolism. During early ischemia, hearts exposed to severe hyperoxia had better ATP and glycogen preservation (p < 0.003). These hearts exhibited almost complete (92%) creatine phosphate depletion, in contrast to incomplete creatine phosphate use in all other neonatal hearts, even in the face of 30% ATP reductions. However, hearts exposed to severe hyperoxia also had a higher incidence of fibrillation during ischemia, which accelerated ATP and glycogen degradation. CONCLUSIONS: Although severe hyperoxia provided an energy-sparing effect during early ischemia, it also increased the incidence of ventricular fibrillation, which negated this beneficial effect.
BACKGROUND: This study examines the effect of neonatal exposure to clinically relevant hyperoxia levels on both in vivo myocardial metabolism and the subsequent metabolic response to global ischemia. METHODS: Three-day-old pigs were ventilated to normoxia (80 mm Hg, 2 or 5 hours, n = 11), mild hyperoxia (250 mm Hg, 2 hours, n = 9), or severe hyperoxia (500 mm Hg, 5 hours, n = 14). Ventricular biopsies obtained at the end of the ventilation period, and at early and late ischemia were analyzed for ATP, ADP, AMP, creatine phosphate, glycogen, and lactate. RESULTS:Hyperoxia did not significantly alter in vivo metabolism. During early ischemia, hearts exposed to severe hyperoxia had better ATP and glycogen preservation (p < 0.003). These hearts exhibited almost complete (92%) creatine phosphate depletion, in contrast to incomplete creatine phosphate use in all other neonatal hearts, even in the face of 30% ATP reductions. However, hearts exposed to severe hyperoxia also had a higher incidence of fibrillation during ischemia, which accelerated ATP and glycogen degradation. CONCLUSIONS: Although severe hyperoxia provided an energy-sparing effect during early ischemia, it also increased the incidence of ventricular fibrillation, which negated this beneficial effect.
Authors: Eddie Chang; Kristie Hornick; Karen I Fritz; Om P Mishra; Maria Delivoria-Papadopoulos Journal: Neurochem Res Date: 2007-03-31 Impact factor: 4.414
Authors: Lukas Peter Mileder; Nicholas Mark Morris; Stefan Kurath-Koller; Jasmin Pansy; Gerhard Pichler; Mirjam Pocivalnik; Bernhard Schwaberger; Ante Burmas; Berndt Urlesberger Journal: Children (Basel) Date: 2021-05-20