One important enzyme that plays a role in the Glu metabolic pathway is glutamine synthetase

using SigmaPlotH version 12 unless otherwise stated. Data were reported as means 6 SEM unless otherwise stated. Results Thermal Tolerance Limits of Cardiac KU-55933 site Function With increasing temperature N. celidotus maintained heart rate until an average temperature of 27.860.4uC . This indicates the critical temperature of heart failure occurs above 27.5uC. The heart rate at the beginning of the experiment for the control fish did not change compared to heart rate at the end of the experiment when the experimental fish had attained THF. Haemoglobin oxygen saturation of experimental fish did not differ from control fish. The percentage change in the 940:600 ratio remained relatively constant in control and experimental animals as temperature gradually increased to THF, and 95% confidence intervals for linear regression overlapped. Metabolite analysis of plasma from the 26669264 cardiac function experiment showed that the only glycolytic intermediate detected was lactate. Lactate levels significantly increased by 1.55fold in experimental plasma, compared to controls. Five TCA cycle intermediates were identified in plasma; citrate, cis-aconitate, a-ketoglutarate, succinate and malate. Citrate, succinate, and malate were consistently detectable in both control and experimental plasma samples. Although citrate appeared to increase in acutely heat stressed plasma, only succinate was Calculations and Statistical Analyses Heart rate was determined using a script written for OctaveH, a numerical computational freeware. The Doppler output signal in AudacityH was converted to WAV format to use with OctaveH which calculates the 10753475 peak frequency heart rate. The signal envelope was first computed using a root mean square approach, and peaks were defined as any part of the signal greater than 50% of the maximum value of the envelope function. Sonogram data were analyzed using a repeated measures ANOVA followed by a post hoc Tukey test with a significance level of P#0.05. In experimental fish, ABT was determined by segmented linear regression using the SegReg program. R2 was Do Mitochondria Limit Hot Fish Hearts significantly elevated and malate was significantly lowered. More essential amino acids were significantly elevated in heat stressed plasma compared to non-essential amino acids . Similar to measures in plasma, lactate trended higher in cardiac tissue of acutely heat stressed fish. The activity of LDH significantly increased by 50%, indicating that heat stressed hearts had up-regulated anaerobic capacities during temperature exposure time while CS and G6PDH remained unchanged with heat exposure. Mitochondrial Bioenergetics Mitochondrial function in heart fibres from fish acutely exposed to heat stress. Following an acute exposure to increasing temperature permeabilized heart fibres showed few differences from control fish. However, experimental fish showed significantly lower Leak-I and OXP-I fluxes, compared to control fish. This significantly depressed the RCR by,22% with temperature exposure. The OXP flux fuelled by CI and CII substrates and uncoupled rates between control and experimental fish remained unaltered. ROS production was significantly elevated when mitochondria were uncoupled, although acute heat stress did not change ROS production in Leak-I, OXP-I or OXP-I, II states. Impacts of in situ heat stress on permeabilized heart mitochondria. All components of mitochondrial phosphorylation were sensitive to increased temperatures. An increase in temperatu