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Mechanism of action of Clostridium perfringens enterotoxin. Effects on membrane permeability and amino acid transport in primary cultures of adult rat hepatocytes
Authors:Olarae Giger  Michael W Pariza
Institution:Department of Food Microbiology and Toxicology, Food Research Institute, University of Wisconsin-Madison, Madison, WI 53706 U.S.A.
Abstract:Purified enterotoxin from the bacterium Clostridium perfringens rapidly decreased the hormonally induced uptake of α-aminoisobutyric acid in primary cultures of adult rat hepatocytes. At 5 min after toxin addition the decrease in α-aminoisobutyric acid uptake appeared not due to increased passive permeation (estimated with l-glucose) or to increased α-aminoisobutyric acid efflux. When short uptake assay times were employed a depression of α-aminoisobutyric acid influx was observed in toxin-treated hepatocytes. The depression of α-aminoisobutyric acid influx was correlated with a rapid increase in intracellular Na+ (estimated using 22Na+) apparently effected by membrane damage. In contrast, the uptake of cycloleucine in the presence of unlabeled α-aminoisobutyric acid (assay for Na+-independent amino acid uptake) by hepatocytes treated with toxin for 5 min was decreased to only a small extent or not at all depending upon experimental design. At later times, C. perfringens enterotoxin increased the exodus of l-glucose, 3-O-methylglucose and α-aminoisobutyric acid from pre-loaded cells indicating that the toxin effects progressive membrane damage. When enterotoxin was removed by repeated washing after 5–20 min the decay of α-aminoisobutyric acid uptake ceased and appeared to undergo recovery towards the hormonally induced control level. The degree of recovery of α-aminoisobutyric acid uptake was inverse to the length of time of exposure to toxin. Adding at 10 min specific rabbit antiserum against C. perfringens enterotoxin without medium change also reversed the effect of toxin on increased intracellular 22Na+, and on the exodus (from preloaded cells) of α-aminoisobutyric acid, L-glucose, and 3-O-methylglucose.
Keywords:Enterotoxin action  Amino acid transport  Bacterial toxin  Membrane permeability  (C  perfringens  Rat hepatocyte)  Hepes  To whom requests for reprints should be addressed  
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