Rat peritoneal mast cells were incubated with different concentrations of naturally occurring aliphatic polyamines, spermine and spermidine, at 0.1-10 mM and the amount of histamine release into the supernatant solutions was measured. The addition of each polyamine to the suspensions of the mast cells caused a histamine release in a dose-dependent manner. The effect of 10 mM spermine and spermidine was as much as that of 0.5 microgram/ml compound 48/80. The histamine release from the cells incubated with each polyamine was rapid and the amount of histamine release into the supernatant solutions reached a maximum at 1 min with the incubations. 0.1 mM spermine, which in itself could not cause a significant histamine release, showed a tendency to enhance anti-IgE-induced histamine release from the mast cells.

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Rat mast cell granules were obtained by homogenization of highly purified rat mast cells and isolated in a Percoll gradient. Diphosphoinositide (DPI) synthesis in rat mast cell granules was assayed by measuring the incorporation of 32P from [gamma 32P] ATP into DPI in the absence of exogenous phosphatidylinositol (PI). Lipids were isolated with methanol/chloroform/HCl and were separated by thin-layer chromatography on oxalic acid impregnated silica gel plates. DPI areas were identified by staining with iodine, scraped and measured for 32P radioactivity. The addition of polyamines, spermine and spermidine, to the granules caused an increase of DPI synthesis, which can be catalyzed by PI kinase. This effect of polyamines in the DPI synthesis was in a dose-dependent manner and maximal effects were observed at 1 mM spermine and 10 mM spermidine, respectively.

These data suggest that A23187 exposure induced AHR to SP possibly by reducing NO levels in the airway tissues. This may be due to damaged airway epithelium and/or NO breakdown by activated inflammatory cells in the airways of these guinea pigs.

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