[Effects of 7 d head-down tilt (-20 degrees) immobilization on pharmacokinetics of gentamicin in rabbits].

OBJECTIVE: To observe pharmacokinetic changes under simulated weightlessness in relevant to body flood flow changes. METHOD: Gentamicin was selected as probe drug in the present study, and rabbits exposed to Head-Down Tilt (HDT, -20 degrees) immobilization were selected as simulated weightlessness animal model. Seven rabbits were treated inf. with 3 mg/kg of gentamicin sulfate pre-HDT and 7 d after HDT. Gentamicin blood samples within 4 h after administration were analyzed by TDxFLx. RESULT: The distribution of gentamicin postponed significantly: a significant decrease in alpha from (0.1838 +/- 0.1076) min-1 before HDT to (0.0591 +/- 0.0334) min-1 after HDT; a significant increase in t1/2 alpha from (5.30 +/- 3.55) min to (15.04 +/- 7.49) min; a significant decrease in k12 from (0.1025 +/- 0.0721) min-1 to (0.0181 +/- 0.0161) min-1, a increase trend in V(C) and V(D). After HDT, CL(S) of gentamicin increased from (2.2 +/- 0.5) ml min-1 kg-1 to (2.7 +/- 0.3) ml min-1 kg-1. CONCLUSION: Simulated weightlessness might induce pharmacokinetic changes.

[Counteracting effect of Chinese herbs-compounds on "blood stasis" induced by bed rest].

Objective. To observe the improved effect of syndromes of blood stasis by taking Chinese medicine during bed-rest simulated weightlessness. Method. Ten subjects were randomly divided into two groups: Chinese medicine group and control group. Both of them were exposed to HDBR -6 degrees for a week. The Chinese medicine group took Chinese medicine during the bed rest, and the control group took sugar water. Result. Syndromes of blood stasis of Chinese medicine group had a significant relief. And some physiological parameters, such as blood pressure, pulse graph, and amount of urine, maintained the level of pre-bed rest. While the control group was more severe than the Chinese medicine group in syndromes of blood stasis. Conclusion. Chinese medicine can be a measure in preventing the effect of weightlessness.

[Counteracting effect of Chinese herbs on "insufficiency of spleen qi" induced by simulated weightlessness].

Objective. To observe the counteracting effect of a Chinese herb-compound on "insufficiency of spleen qi" induced by simulated weightlessness. Methods. Animal and human experiment were carried out to the Chinese herb-compound (Dangshen, Baizhu, Fuling etc). Result. This compound protected the tail suspended rats from atrophy of spleen, thymus, soleus and gastrocnemius muscles, prevented excessive decrease of body weight effectively; at the same time it relieved the symptoms of the subjects greatly. Conclusion. It demonstrated that the compound decreased the "insufficiency of spleen qi" of both animals and human subjects.

[Comparison between two anti-motion sickness drugs].

Objective. To test the validity of an animal model in selecting anti-motion sickness drugs, and compare the effects of two drugs. Method. Anti-motion sickness effects of two drugs (Cyclizine and Scopolamin-d-amphetamin compound) were observed in rats with motion sickness (MS) induced by rotatory stimulation and the amount of Kaolin ate by rats was taken as an evaluation criterion. Result. The consumption of Kaolin by the rats decreased significantly after administration of both drugs, and the effect of Scopolamin-d-amphetamin compound was better than those of Cyclizine under the same condition. Conclusion. It suggests that the rat model of motion sickness is practical and useful in studying anti-motion sickness drugs.

Medicinal protection with Chinese herb-compound against radiation damage.

Experiments were carried out on mice and the subjects irradiated for cancer therapy to evaluate the protective efficacy of a Chinese medicinal herb-compound (CMHC). The lethality and the degree of leucopenia caused by radiation in mice medicated with CMHC were significantly less in comparison with control mice (p less than 0.01 and p less than 0.001, respectively). CMHC significantly improved the WBC and the thrombocytes in irradiated workers (p less than 0.01 and p less than 0.001, respectively). The WBC count of 40 patients under radiotherapy while treated with CMHC recovered from 3450 +/- 77/c.mm to 5425 +/- 264/c.mm (p less than 0.001); whereas, in the control group, without any medication, the WBC count dropped significantly (p less than 0.001). Our results revealed the applicabilities of CMHC in protection against radiation damage in spaceflight and in other fields.