Effect of endotoxin, dobutamine and dopamine on muscle mitochondrial respiration in vitro.
BACKGROUND
Mitochondrial respiration is impaired during endotoxemia. While catecholamines are frequently used in sepsis, their effects on mitochondrial function are controversial. We assessed effects of dobutamine and dopamine endotoxin on isolated muscle mitochondria.


METHODS
Sternocleidomastoid muscle mitochondria were isolated from six anesthetized pigs. Each sample was divided into six different groups. Three groups were incubated with endotoxin, three with vehicle. After 1 h, dopamine and dobutamine at final concentrations of 100 microM were added to the vehicle and endotoxin groups. After 2 h, state 3 and 4 respiration rates were determined for all mitochondrial complexes. Oxygen consumption was determined with a Clark-type electrode.


RESULTS
Endotoxin increased glutamate-dependent state 4 respiration from 9.3 +/- 3.6 to 31.9 +/- 9.1 (P = 0.001) without affecting state 3 respiration. This reduced the efficiency of mitochondrial respiration (RCR; state 3/state 4, 9.9 +/- 1.9 versus 3.6 +/- 0.6; P < 0.001). The other complexes were unaffected. Catecholamine partially restored the endotoxin-induced increase in complex I state 4 respiration rate (31.9 +/- 9.1 versus 17.1 +/- 6.4 and 20.1 +/- 12.2) after dopamine and dobutamine, respectively (P = 0.007), and enhanced the ADP:O ratio (P = 0.033).


CONCLUSIONS
Dopamine and dobutamine enhanced the efficiency of mitochondrial respiration after short-term endotoxin exposure.
Porta
Francesca
F
Department of Intensive Care Medicine, University Hospital Bern, 3010 Bern, Switzerland.
Takala
Jukka
J
Weikert
Christian
C
Kaufmann
Priska
P
Krahenbuhl
Stephan
S
Jakob
Stephan M
SM
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D004280:Dobutamine / Q000494:pharmacology*; D004298:Dopamine / Q000494:pharmacology*; D004731:Endotoxins / Q000633:toxicity*; D005260:Female; D007700:Kinetics; D008297:Male; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*; D013552:Swine
D004731:Endotoxins; D004280:Dobutamine; D000244:Adenosine Diphosphate; D004298:Dopamine