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Objective To investigate the radioprotective effect of cimetidine on survival rate and hematopoietic system in acutely irradiated mice.Methods The total body irradiation doses were 6.0Gy and 8.0Gy respectively at 1.01Gy/min rate. Sixty healthy male C57BL/6 mice were randomly divided into control group, model group, positive-drug (523) group and cimetidine groups (33.3mg/kg, 100mg/kg and 300mg/kg). Each group had ten mice. The mice were given intragastric administration of cimetidine for 6d before the irradiation in cimetidine groups, and 523 was administered before irradiation once a day for one day in 523 group, and at 5h after irradiation, was given again. The 30d survival rate after 8.0Gy irradiation was recorded. The peripheral blood cells, bone marrow DNA content and frequency of micronucleated polychromatic erythrocytes (fMNPCE) were determined 30d after 6.0Gy irradiation.Results After 8.0Gy irradiation, all the mice died on 21th day in model control group. The survival rates in cimetidine groups were 50%, 20% and 30%, respectively. After 6.0Gy irradiation on 30th day, compared with control group, the peripheral white blood cells (WBC) and bone marrow DNA content were decreased significantly (P<0.01,P<0.05) in model group, and fMNPCE was increased significantly (P<0.05). Compared with model group, WBC was significantly increased in 300mg/kg cimetidine group (P<0.01). In cimetidine groups, the bone marrow DNA content was increased significantly after irradiation (P<0.01 orP<0.05), and the fMNPCE was decreased significantly (P<0.01 orP<0.05) and tended towards normal.Conclusion Cimetidine could improve 30d survival rate of acutely irradiated mice and has good protective effect on hematopoietic system.
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AIM: To compare the effects of histamine and its antagonists on tension of isolated rabbit basilar and mesenteric artery in vitro, and to observe the role of Ca 2+ in histamine induced response. METHODS: The dose response curves induced by histamine were recorded on the isolated rabbit central and peripheral arteries in different doses of diphenhydramine, cimitidine, and nifidipine. RESULTS: Histamine could cause contraction of basilar and mesenteric isolated arteries. Diphenhydramine and nifidipine antagonized these effects, while cimitidine enhanced this effect. CONCLUSION: There may be different receptors densities in different rabbit arteries; histamine shows the vasoconstrictive effect on both brain and mesenteric arteries; and the vasoconstrictive effect mainly produces via Ca 2+ inflax.
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The effects of a new crystallization form A famotidine ( F_A ) on experimental gastric ulcers in rats, and compared the antiulcer effects of F_A with those of the form B of famotidine(F_B)were investigated . F_B has been used in clinic.The results showed that the anti-ulcer effects of F_A were as same as F_B and both of F_A and F_B were dose- dependent manner.