Effect of platelet-activating factor on basal and insulin-mediated system A amino acid transport in rat soleus muscle.
We investigated the effect of platelet-activating factor (PAF) on basal and insulin-stimulated sodium-dependent neutral amino acid transport by system A in rat soleus muscle. Fasted male Sprague-Dawley rats (75-100 g) were given an intravenous injection of saline or PAF (4 micrograms/kg) and killed 1 hr later. Isolated soleus muscles were incubated in media containing 1-14C-alpha-aminoisobutyric acid (AIB; system A amino acid analog), 3H-inulin, and 0 (basal) or 100 mU/ml insulin. Na(+)-free media were assessed by Na(+)-independent AIB uptake. The rate of AIB uptake by muscle was corrected for uptake into extracellular (inulin) space. Basal cellular AIB uptake by soleus muscles from PAF-treated rats was 30.2% lower than in controls. Insulin increased the absolute rate of cellular AIB uptake above basal levels to the same extent in muscles of control and PAF-treated rats, although the rate of maximal insulin-stimulated AIB uptake was 20% lower in muscles of PAF-treated rats. Na(+)-independent AIB uptake (measured in Na(+)-free media) was the same in muscles of control and PAF-treated rats. The fact that AIB uptake in Na(+)-free media was the same in muscles of control and PAF-treated rats indicates that the reduction in basal and insulin-stimulated AIB uptake in muscles of PAF-treated rats was due to an alteration of system A Na(+)-dependent amino acid transport.
Boruff
J S
JS
Department of Anesthesiology, Graduate School of Medicine, University of Tennessee Medical Center, Knoxville 37920.
Karlstad
M D
MD
D000596:Amino Acids / Q000378:metabolism*; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004195:Disease Models, Animal; D007328:Insulin / Q000494:pharmacology; D007444:Inulin / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D010972:Platelet Activating Factor / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012772:Shock, Septic / Q000378:metabolism*; D012964:Sodium
D000596:Amino Acids; D000621:Aminoisobutyric Acids; D007328:Insulin; D010972:Platelet Activating Factor; C100049:2-aminoisobutyric acid; D007444:Inulin; D012964:Sodium