The actions of the polyamines compound 48/80, poly-l-lysine and polymyxin B on rat pleural and peritoneal mast cell secretion have been studied. Unpurified pleural mast cells released more histamine than peritoneal mast cells when stimulated by submaximal concentrations of compound 48/80 and poly-l-lysine, but the same profile of response was observed with polymyxin B in both populations. Dose-response studies of peritoneal and pleural mast cells purified with Percoll and Ficoll and stimulated by polymyxin B showed a decreased sensitivity and decreased maximum response of peritoneal cells when Percoll was used. The maximal response of pleural cells and the sensitivity of peritoneal cells were affected only slightly by Ficoll.

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The effect of high-protein fish meal on maltase and leucine aminopeptidase (LAPase) activities of the intestinal mucosa as well as the renal LAPase activity was studied. Four groups of female Wistar rats, weighing between 40–60 g, were fed diets with a 4 or 12% protein content of dry matter for 25 days. The protein source was casein for the control groups and fish meal derived from Coryphaenoides rupestris for the test groups. The results show a decrease (p < 0.005) in intestinal maltase and LAPase activities and renal LAPase activity in animals fed with 12% offish meal protein compared to those fed with casein, while the rats fed 4% offish meal protein showed a decrease in intestinal maltase activity and no significant difference in LAPase activity compared with the control group. These results seem to indicate that the intestinal maltase is influenced by the quality and quantity of dietary protein, while the intestinal and renal LAPase activity is only changed by the quality of protein.

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