Chapter XII 



COMPARISON OF THE EFFECTS OF THE SAME HISTAMINE- 



LIBERATOR (COMPOUND 48 80) ON TWO CLOSELY ALLIED 



SPECIES, MOUSE AND RAT 



{See Riley and West, 19556) 



THE work described in the previous section indicates clearly that com- 

 pound 48/80 is a specific and highly effective histamine-liberator for the 

 rat, releasing histamine from its depots in the tissue mast cells. However, 

 other workers have shown that compound 48 80 is less effective as a histamine- 

 liberator in certain other species, notably the guinea pig (Feinberg and 

 Sternberger, 1955). It was thus of interest to compare its effects on 

 two closely allied species, the mouse and rat. As before, the action of the 

 liberator was studied both in short-term and in long-term experiments. 



Methods 



The present study involved the use of ninety-four young male rats (weight 

 90-110 g.) of the Wistar strain, and 126 male albino mice (weight 19-21 g.). 

 To obtain representative initial values for the histamine content of tissues, four 

 groups of six rats and four groups of nine mice were killed by a blow on the 

 head, and pooled tissues from each group were assayed. The experimental 

 animals were killed in groups of seven rats and often mice, as follows: 



Short-term experiment, at days 3, 5, 11, 15, 18, 32 (rats); and 3, 8, 15, 21, 



32 (mice). 

 Long-term experiment, at days 5, 15, 24, 32 (rats); and 3, 8, 15, 21, 32 (mice). 



On each occasion one animal chosen at random from each group was used for 

 histological purposes, pooled tissues from the remainder being assayed for 

 histamine. 



The histamine-liberator, compound 48/80, kindly supplied by Messrs. 

 Burroughs Wellcome and Co., was made up in fresh normal saline for injection 

 intraperitoneally low down on the abdominal wall, the dosage being as follows: 



Short-term experiment: Rats — injections twice daily (9 a.m. and 5 p.m.), 

 starting at 100 \xg. per dose and increasing the doses by 100 \xg. each day to 

 reach doses of 500 \xg. on the fifth day. 



Mice — injections twice daily, starting at 50 \xg. per dose and increasing 

 the doses by 50 \±g. each day till the fourth day when doses of 1 50 [xg. and 200 \xg. 

 were used. On the fifth day both doses were of 200 \xg. 



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