Male Hartley guinea pigs from {TAIL ~ Charles River}, weighing 250 275 grams on {HEAD ~ arrival} and 300 600 grams at testing, serve as subjects in the experiment 
Male Hartley guinea pigs from { TAIL ~ Charles River } , weighing 250 275 grams on { HEAD ~ arrival } and 300 600 grams at testing , serve as subjects in the experiment
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