Studies of the activities of Ca-ATPase AND H-K-ATPase of erythrocyte in high risk population for sudden unexplained death syndrome in the Northeast Thailand
Abstract:
Problem : Northeast Thailand there is a high incidence of Sudden Unexplained Death Syndrome (SUDS). It is believed that ventricular fibrillation and /or ventricular tachycardia might be the cause of death. Previous report has shown that Near missed Sudden Unexplained Death Syndrome (N SUDS0 had a higher concentration of erythrocyte sodium and lower activities of erythrocyte Na,K-ATPase than central Thais. It is speculated without proof that might be alterlation in intracellular calcium and pH as well as other transporting enzyme on cell membrane. Objective : Study erythrocyte calcium, intra erythrocyte membrane Ca-ATPase ,H,K-ATPase in the following populations : N-SUDS ,healthy Northeast Thai villager (V-NE) , healthy Northeast Thai who have been living in Bangkok for more than 12 months ( M-NE) and healthy control Thai in Bangkok(BKK) Result: There was no difference in age among the 4 groups [ N SUDS = 36.9 ± 7.2 years, V NE = 35.6 ± 8.8 years , M NE = 30.0±7.6 years and BKK = 37.3 ± 9.5 years ( mean±SEM )]. The Cai in BKK was [23.76±4.54 nmol/L( mean ± SEM) ] similar to to what previously reported , whereas N-SUDS had higher Cai ( 91.9 ± 13.69 nmol / L) than BKK, V-NE and M-NE ( 59.26 ± 11.68 and 54.65 ± 6.57 nmol / L ) (p<0.05) .Let the mean±2SD value of Cai in Bangkok group represent the upper limit of normal range. Cai of N-SUDS,V-NE and M-NE was higher cut of point 75, 58.3 and 41.7 % respectively . Erythrocyte pH values of N-SUDS, V-NE and M-NE [ 7.231 ± 0.012 , 7.237 ± 0.007 and 7.259 ± 0.007 respectively] were lower than BKK[ 7.289±0.017 ] .There was significantly lower Ca-ATPase in V-NE than that in BKK (298.03 ± 14.35nmolPi/mg.protein/hr.) Ca-ATPase of N-SUDS ,V-NE and M-NE was lower cut of point 75 ,33.3 and 25% respectively). There was difference in erythrocyte H,K-ATPase among N-SUDS, V-NE, M-NE and BKK However about 58,47 and 8.3% had high erythrocyte H,K-ATPase in N-SUDS, V-NE and M-NE . There were negative correlation between Cai and Ca-ATPase (r2 = 0.310 p<0.001) , pHi and H,K-ATPase(r2= 0.078 p<0.001) Conclusion : This studied suggest that N-SUDS tend to have higher Cai and lower pHi and activity of Ca-ATPase H,K-ATPase. These abnormality was more prominent any V-NE ,M-NE .High Cai could be caused by low activity of erythrocyte Ca-ATPase. Erthrocyte pH might be go tolow H,K-ATPase or other modified mechanisms. There may be a relationship between these abnormalities and Sudden Unexplained Death Syndrome.