AJP - Regulatory, Integrative and Comparative Physiology, Vol 252, Issue 4 674-R680, Copyright © 1987 by American Physiological Society
Effect of endotoxic shock on skeletal muscle intracellular electrolytes and amino acid transport
M. D. Karlstad and M. M. Sayeed
Soleus muscle intracellular electrolytes and alpha-aminoisobutyric acid
(AIB) uptake and its regulation by insulin were investigated during
endotoxic shock in vivo. Fasted rats (90 g) were injected with [14C]AIB
(1-10 mg/kg, iv) and Salmonella enteritidis endotoxin (20 mg/kg, iv) or
saline and killed 1-5 h later. AIB uptake into muscle was corrected for
uptake into extracellular space (measured as insulin distribution in muscle
in vivo) and expressed as [AIB]/[AIB] ratios to assess active transport.
The maximum level of active AIB cell transport by extracellular endotoxic
muscles [3.3 +/- 0.2 (SE)] was lower than control muscles (4.9 +/- 0.3) at
the time when plasma insulin concentration in endotoxic rats (16.8 +/- 2.0
uU/ml) was greater than controls (7.9 +/- 1.7 uU/ml). Insulin-stimulated
AIB transport was significantly lower in endotoxic muscles (from a basal
value of 3.3 +/- 0.2 to 4.4 +/- 0.5, 5.0 +/- 0.3, and 4.9 +/- 0.3 at 125,
250, and 500 mU/kg intravenous insulin, respectively) than in control
muscles (from 4.9 +/- 0.3 to 5.7 +/- 0.2, 8.0 +/- 0.4, and 10.8 +/- 0.8).
The intracellular electrolyte concentrations in endotoxic soleus muscles
([Na] = 15.87 +/- 0.9, [K] = 145 +/- 1.7, [Cl] = 14.61 +/- 0.9) were
substantially altered when compared with control muscles ([Na] = 9.33 +/-
1.1, [K] = 164 +/- 1.5, [Cl] = 4.1 +/- 0.6) 5 h postinjection. The membrane
potential, estimated from chloride equilibrium potential was lower in
endotoxic muscles (-52.7 +/- 1.6 mV) when compared with control muscles
(-89 +/- 3.5 mV).(ABSTRACT TRUNCATED AT 250 WORDS)
