Properties of the histamine stores affected in the anaphylactic and anaphylatoxin shock of the guinea pig: I. Effect of pretreatment with anaphylatoxin

1. Sensitized guinea pigs were protected with antihistamine and slowly injected (within 3 min) with antigen. 50% of the animals survived. After rapid injection of the same antigen dose (≙ 20 mg/kg ovalbumin) all animals died. 2. The lung histamine content was decreased to about half of the normal value in animals which died during the treatment as well as in surviving guinea pigs. 1 week later the lung histamine content was again within the normal range. 3. During this period an additional anaphylactic shock resulted only in a small reduction of the overall lethality (about 20%). Although no antihistamine had been given the animals died significantly later. Plasma histamine levels were depressed, sometimes to about 1/10 of the values found normally in anaphylactic shock. The lung histamine content did increase from 2 to 5 μg per g tissue. All parameters measured were normal 1 week after the antigen infusion. 4. During the same period of time the lethality of an anaphylatoxin shock was not reduced. Plasma histamine levels were diminished whereas the histamine content of the lungs did increase. As compared to an anaphylatoxin shock in unpretreated animals not exposed to antigen plasma histamine levels were in the normal range after 1 day. At this moment lung histamine content was still reduced by the antigen pretreatment. 5. We assume that the guinea pig lung contains two different histamine pools, one having a short half-life (less 1 day) and being depleted in anaphylatoxin shock, the other recovering more slowly (within 1 week), and being released in addition in anaphylaxis. The first one corresponds well with the properties of the non-mastcell-store described by Brodie et al. (1966), the latter seems to be identical with the typical mastcell-pool.