Comparative studies between germ-free and conventional mice were made as to the bone marrow reactions to E. coli endotoxin and Pseudomonas aeruginosa OEP. With the direct smear method of the bone marrow reactions, it was found that conventional mice were more vulnerable than germ-free mice. Conventional mice were more sensitive also as to lethality. With the absolute count method of the bone marrow reactions, conventional mice were more vulnerable than germ-free mice on the increase of red blood cell number in the marrow which reflected damage of the circulation, whereas germ-free mice were more sensitive than conventional mice as to the decrease of nucleated cell number in the marrow which resulted from leukopenia and leukocytosis in the peripheral circulation. This finding as to the nucleated cell number was more remarkable in mice given OEP than in the mice given endotoxin.

Animals↗

PubMed1975

Inhibitory effects of antihistamines and antiserotonins on the bone marrow reactions produced by Escherichia coli endotoxin in mice.

The bone marrow reactions (that is, decrease of nucleated cell counts and increase of red blood cell counts) of mouse bone were observed 1 hr after injection of endotoxin and peaked after 18 hr. These reactions were significantly inhibited when diphenhydramine, promethazine (antihistamines), chlorpromazine (antiserotonin), or cyproheptadine (antihistamine and antiserotonin) was given 30 min before endotoxin. Such bone marrow reactions were also induced with histamine or serotonin and peaked 1 hr after administration. The histamine-induced changes were inhibited by prior treatment with diphenhydramine. These reactions were also produced by injection of a small amount of both histamine and serotonin, whereas no change was found when mice were given a single injection of a larger dose of histamine or serotonin. These results indicate that histamine and serotonin released in mice at the initial stage after endotoxin synergistically trigger the bone marrow reactions, which then continue in the presence of further mediators. Antihistamines and antiserotonins are considered to hinder the whole process of reactions produced by endotoxin.

Animals↗

PubMed1975

A hexapeptide angiotensin antagonist, Des-(Asp1, Arg2), Ile8)-angiotensin II.

In the smallest biologically active fragment of angiotensin or a 3-8 hexapeptide the C-terminal was substituted by isoleucine residue. It proved to be the smallest potent antagonist of angiotensin II so far reported.

Angiotensin II↗

PubMed1975