TY - JOUR
T1 - Sulfide-inhibition of mitochondrial respiration at very low oxygen concentrations
AU - Matallo, J.
AU - Vogt, J.
AU - Mccook, O.
AU - Wachter, U.
AU - Tillmans, F.
AU - Groeger, M.
AU - Szabo, C.
AU - Georgieff, M.
AU - Radermacher, P.
AU - Calzia, E.
N1 - Funding Information:
This work was supported by the Deutsche Forschungsgemeinschaft ( KFO 200 , DFG RA396/9-2 ), the Land Baden-Württemberg (Innovationsfond Medizin) , and is part of the PHYPODE project, financed by the European Union under a Marie Curie Initial Training Network.
PY - 2014/9/15
Y1 - 2014/9/15
N2 - Our aim was to study the ability of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the rate of elimination of sulfide through the pathway linked to the mitochondrial respiratory chain and therefore operating under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide's inhibition of cellular respiration would occur faster under continuous sulfide exposure when the oxygen concentration is in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5-1 ×106 cells in 2 ml of continuously stirred respiration medium at 37 °C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73 ± 0.05 μM, 3.1 ± 0.2 μM, and 6.2 ± 0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3;3.5] and 11.7 [6.2;21.2] min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6 [15.5;28.1] min (coupled) and 35.9 [27.4;59.2] min (uncoupled), as well as 42.4 [27.5;42.4] min (coupled) and 51.5 [46.4;51.7] min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results confirm that the onset of inhibition of cell respiration by sulfide occurs earlier under a continuous exposure when approaching the anoxic condition. This property may contribute to the physiological role of sulfide as an oxygen sensor.
AB - Our aim was to study the ability of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the rate of elimination of sulfide through the pathway linked to the mitochondrial respiratory chain and therefore operating under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide's inhibition of cellular respiration would occur faster under continuous sulfide exposure when the oxygen concentration is in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5-1 ×106 cells in 2 ml of continuously stirred respiration medium at 37 °C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73 ± 0.05 μM, 3.1 ± 0.2 μM, and 6.2 ± 0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3;3.5] and 11.7 [6.2;21.2] min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6 [15.5;28.1] min (coupled) and 35.9 [27.4;59.2] min (uncoupled), as well as 42.4 [27.5;42.4] min (coupled) and 51.5 [46.4;51.7] min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results confirm that the onset of inhibition of cell respiration by sulfide occurs earlier under a continuous exposure when approaching the anoxic condition. This property may contribute to the physiological role of sulfide as an oxygen sensor.
KW - Hypoxia
KW - Mitochondrial respiration
KW - Sulfide
KW - Sulfide-quinone-oxidoreductase
UR - http://www.scopus.com/inward/record.url?scp=84907598486&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84907598486&partnerID=8YFLogxK
U2 - 10.1016/j.niox.2014.06.004
DO - 10.1016/j.niox.2014.06.004
M3 - Article
C2 - 24963794
AN - SCOPUS:84907598486
SN - 1089-8603
VL - 41
SP - 79
EP - 84
JO - Nitric Oxide - Biology and Chemistry
JF - Nitric Oxide - Biology and Chemistry
ER -