altitude conditions (6500m, oxygen 11%). The animals were divided into three groups: the
control group was injected with normal saline (100_l), the experimental group 1 was injected
with naloxone (40_g/_l), and the experimental group 2 was injected with picrotoxin (10_g/100_l)
into the fourth ventricle. Results: The results indicated that the HR (heart rate) in the three groups
and MAP (mean arterial pressure) in the experimental group 1 did not significantly change at 5-
10 minutes after normoxia. MAP in the experiment group 2 was remarkably increased during
normoxia. The HR and MAP in the control group was significantly decreased during acute
hypoxia, and returned to normal levels after 5-10 minutes normoxia. The HR in the experimental
group 1 presented a remarkable decrease and the MAP did not change during acute hypoxia.
These results suggested that the decrease of MAP during hypoxia was blocked by naloxone. The
HR in the experimental group 2 showed a significant decrease as compared with the control
group during hypoxia (p<0.01), but the MAP showed a significant increase during early period of
hypoxia, and then maintained the control level. Conclusions: The endogenous opioid peptides do
not participate in the central nervous system regulation of cardiovascular activity and GABA can
inhibit cardiovascular activity under normal conditions. The MAP decrease in the rabbit during
hypoxia is related to the increase of endogenous opioid peptide activity and GABA system in the
medulla.
103.
STUDY ON THE PATHOGENESIS OF MOUNTAIN FROSTBITE. Liu Jia-Ying
1
, Yang Zen-
Gren
1
, Li Feng-Zhi
1
, Yan Pei-Hua
1
. Institute of Hygiene and Environmental Medicine
1
.
To explore the pathogenesis of mountain frostbite, local frostbite in animals at simulated
altitude was studied. Methods: Wistar rats and hamsters were randomly divided into three groups,
i.e. frostbite at normoxia (FN), frostbite during acute hypoxia (FAH) and frostbite during hypoxia
after acclimation (FHAC). After subjecting the animals in group FHAC to intermittent hypoxia
for 4 weeks, the hind feet of rats and the cheek pouches of hamsters were frozen to produce
severe frostbite in group FAH and FHAC at hypoxia and FN at normoxia. The rectal temperature
(Tr), skin temperature of frostbitten feet (Ts), coagulation time, serum creatine kinase (CK)
activity, parameters of hemorheological behavior, tissue survival area (TSA) of frostbitten feet,
and changes in microcirculation in cheek pouches of hamsters and in pathological were
investigated. Results: The results of TSA of the frostbitten feet and serum CK activity indicated
that tissue damage of mountain frostbite in rats acclimated to hypoxia was aggravated. Ts
measurments showed the disturbance of blood circulation was more severe in the FHAC group
than in FN or FAH groups. In rats acclimated to hypoxia, the parameters of hemorheological
behavior worsened, and worsened much more after freezing. The abnormality of coagulation time
in the group FHAC was present for a longer time than in the FN or FAH groups; the blood in the
group FHAC remained in a hypercoagulation state persistently. Microcirculation and pathological
investigations showed that vascular endothelial cells were injured more severely in the group
FHAC than in the FN pr FAH group. Conclusion: Hypoxia-acclimation results in disorders of
blood circulation and decreased blood flowing to peripheral tissues which, on that basis, would be
expected to aggravate the response to freezing. Therefore, hypoxia-acclimation in animals
worsens tissue damage in mountain frostbite.
104.
OBESITY IS A RISK FACTOR FOR CHRONIC MOUNTAIN SICKNESS . Gao Ji-Dong
1
, Dai
Qing-Xiang
1
, Xu Hui-Ning
1
, Yang Qing-Yan
2
, Zhan Xiao-Yan
1
, Han Hui-Ying
1
, Xiao Hui-Ning
1
.
Affiliated Hospital of Qinghai Medical College, Xining. China
1
, Affiliated Hospital of Qinghai
Medical College, Xining. China
2
.
There are some cases of obesity among patients with chronic mountain sickness (CMS), but
which characteristic of obesity makes persons susceptiple to CMS remains to be investigated at
high altitude. Methods: In 2002, 45 Tibetan and 32 Han residents (65 male and 12 female) with a
mean age of 42.31±10.90 years at an altitude of 3702m in Qinghai Province were studied. The
average time the subjects had lived at high altitude was 32.39±17.61 years. The hemoglobin (Hb),
hematocrit (Hct), and fasting plasma glucose (FPG) were measured as were right pulmonary
