Tosukhowong P, Tungsanga K, Kittinantavorakoon C, Chaitachawong C, Pansin P, Sriboonlue P, Sitprija V
Department of Biochemistry, Chulalongkorn University, Bangkok, Thailand.
Metabolism. 1996 Jul;45(7):804-9. doi: 10.1016/s0026-0495(96)90150-x.
Healthy northeastern Thais have a higher erythrocyte sodium concentration and a lower erythrocyte membrane Na,K-adenosine triphosphatase (ATPase) activity than central Thais. To elucidate whether the defect is hereditary or acquired, we studied plasma sodium and potassium and erythrocyte sodium, potassium, Na,K-ATPase activity, and ouabain-binding sites (OBS) in the following groups: healthy newborns of ethnic central Thais (group 1), healthy newborns of ethnic northeast Thais (group 2), healthy adults of central Thailand ethnicity who lived in the rural central region (group 3) or in Bangkok (group 4), healthy adults of northeast Thailand ethnicity who lived in the rural northeast region (group 5) or who migrated to work in Bangkok for at least 1 year (group 6). Erythrocyte Na was higher in group 2 than in group 1. Group 3 had lower erythrocyte Na,K-ATPase activity than group 4, and it was lower in group 5 than in group 6. Among all groups, group 5 had the highest erythrocyte Na (11.6 mmol/L,F < 0.0001) and the lowest Na,K-ATPase activity (63 mmol Pi/mg x h, F < 0.0001) and erythrocyte OBS (397 sites per cell, F < 0.05) than the other adult groups. There was a positive correlation between erythrocyte Na,K-ATPase and erythrocyte OBS (r = .416, P < .0001). Multiple regression analysis demonstrated a correlation between erythrocyte Na as a dependent variable and erythrocyte OBS, plasma potassium, erythrocyte potassium, and erythrocyte Na,K-ATPase (r = .517, P < .0001). The erythrocyte Na,K-ATPase/OBS ratio, an expression of Na,K-ATPase activity equalized for the number of Na,K-pump units, was lowest among rural adults of the central region (group 3) and the northeast region (group 5) (F < 0.0002). Our data suggest that rural dwellers in Thailand tend to have lower erythrocyte Na,K-ATPase activity than urban dwellers and that this is probably acquired after birth. It was more severe among those from the northeast versus the central region, and was less severe among those who migrated to an urban area. This defect in northeast rural dwellers was probably associated with low numbers of Na,K-pump units and a defect of the pump to express activity, whereas in central rural dwellers it was probably associated with the latter condition. We postulate that there might be circulating Na,K-pump inhibitors and metabolic disturbances that cause attenuation of Na,K-ATPase function and synthesis in the northeast Thailand rural population, and that such substances may have an environmental origin. There may be a relationship between these abnormalities and sudden unexpected deaths.
与泰国中部人相比，健康的泰国东北部人红细胞钠浓度较高，而红细胞膜钠钾 - 三磷酸腺苷酶（ATP酶）活性较低。为了阐明这种缺陷是遗传性的还是后天获得的，我们研究了以下几组人群的血浆钠和钾、红细胞钠、钾、钠钾ATP酶活性以及哇巴因结合位点（OBS）：泰国中部民族的健康新生儿（第1组）、泰国东北部民族的健康新生儿（第2组）、居住在泰国中部农村地区（第3组）或曼谷（第4组）的泰国中部民族健康成年人、居住在泰国东北部农村地区（第5组）或迁移到曼谷工作至少1年的泰国东北部民族健康成年人（第6组）。第2组的红细胞钠含量高于第1组。第3组的红细胞钠钾ATP酶活性低于第4组，第5组低于第6组。在所有组中，第5组的红细胞钠含量最高（11.6 mmol/L，F < 0.0001），钠钾ATP酶活性最低（63 mmol Pi/mg×h，F < 0.0001），红细胞OBS最少（每细胞397个位点，F < 0.05），与其他成年组相比。红细胞钠钾ATP酶与红细胞OBS之间存在正相关（r = 0.416，P < 0.0001）。多元回归分析表明，以红细胞钠作为因变量与红细胞OBS、血浆钾、红细胞钾和红细胞钠钾ATP酶之间存在相关性（r = 0.517，P < 0.0001）。红细胞钠钾ATP酶/OBS比值是根据钠钾泵单位数量进行标准化的钠钾ATP酶活性表达，在中部地区（第3组）和东北部地区（第5组）的农村成年人中最低（F < 0.0002）。我们的数据表明，泰国农村居民的红细胞钠钾ATP酶活性往往低于城市居民，这可能是出生后获得的。在东北部人群中比中部人群更严重，而在迁移到城市地区的人群中则较轻。东北部农村居民的这种缺陷可能与钠钾泵单位数量少以及泵表达活性的缺陷有关，而中部农村居民的缺陷可能仅与后者有关。我们推测，在泰国东北部农村人群中可能存在循环的钠钾泵抑制剂和代谢紊乱，导致钠钾ATP酶功能和合成减弱，并且这些物质可能源于环境。这些异常情况与意外猝死之间可能存在关联。
