Most present animal studies on high altitude polycythemia, both at home and abroad, are taken under the circumstance of simulated altitude rather than on the real plateau. Therefore, further studies are still needed to determine how long it will take for plain rats to get this disease at the real high altitude.OBJECTIVE:
To establish animal models with high altitude polycythemia and preliminarily analyze their physiological functional responses to hypoxia.DESIGH, TIME AND SETTING:
A randomized control animal experiment was completed in the Research Center for High Altitude Medicine in Medical College of Qinghai University (the Key Lab of National Ministry of Education and Qinghai Province) from August to September in 2007.MATERIALS:
A total of 50 Wistar rats of SPF grade were used, half male and half female, weighting 160 g to 200 g. Ten plateau pikas were captured at 4 300 m altitude in Maduo County, Qinghai Province, China. Eythropoietin (EPO) kit was offered by R&D Systems Company, USA.METHODS:
Of all the 50 Wistar rats, 30 ones were randomly divided into a high altitude 15-day group (15-day group) and a high altitude 30-day group (30-day group), with 15 rats (of both genders) in each group. Then they were moved to 4 300 m altitude in Maduo County, Guoluo Prefecture, Qinghai Province, China, and were fed there for 15 and 30 days respectively. The other 20 ones were fed, as the low altitude control group, at 2 260 m altitude in Xining, Qinghai Province, China. The 10 pikas were classified as the high altitude control group. The hemoglobin (Hb), haematocrit (Hct) and serum EPO level of all rats was determined at days 15 and 30 following feeding.MAIN OUTCOME MEASURES:
①The number of rats who presented with high altitude polycythemia in the 15-day and the 30-day group. ②The comparison of Hb levels between rats with high altitude polycythemia and those in the two control groups. ③The comparison of serum EPO levels between rats with high altitude polycythemia and those in the two control groups. ④The correlation of Hb levels with both Hct levels and arterial oxygen saturation (SaO2) levels in rats with high altitude polycythemia.RESULTS:
Hb and Hct levels of rats increased remarkablely in both the 15-day group and the 30-day group, and these differences are all of significance compared with either the high altitude or the low altitude control group (P < 0.01). In addition, 75% rats had got HG levels over 207 g/L and Hct levels over 65% in the 15-day group, and 93% ones in the 30-day. EPO levels of rats in both the15-day and the 30-day group were obviously higher than those in the high altitude control group and the low altitude control group (P < 0.01).CONCLUSION:
Based on the physiological indexes of the Wistar rats in this study, we conclude that only after 30 days of feeding at 4300 m altitude can the animal model of high altitude polycythemia be successfully established, and also that animals in lower altitude have different physiological responses mechanisms corresponding to different altitudes.