CHANGES IN CYTOPLASMIC PH IN PLATELETS ACTIVATED THROUGH THE HIGH-AFFINITY AND MODERATE-AFFINITY RECEPTOR PATHWAYS BY HIGHLY PURIFIED HUMAN ALPHA-THROMBIN

被引：0

作者：

JONES, GD ^{[1
]}

TENNER, TE ^{[1
]}

GRECO, NJ ^{[1
]}

KITAGAWA, S ^{[1
]}

TANDON, NN ^{[1
]}

JAMIESON, GA ^{[1
]}

机构：

[1] AMER RED CROSS,DEPT CELL BIOL,15601 CRABBS BRANCH WAY,ROCKVILLE,MD 20855

来源：

JOURNAL OF LABORATORY AND CLINICAL MEDICINE | 1993年 / 121卷 / 05期

关键词：

D O I：

暂无

中图分类号：

R446 [实验室诊断]; R-33 [实验医学、医学实验];

学科分类号：

1001 ;

摘要：

Platelets in plasma were loaded with the probe BCECF/AM, and changes in cytoplasmic pH levels induced by highly purified human alpha-thrombin (2900 NIH U/mg) were studied in washed platelets having high- and moderate-affinity receptors and in platelets from which the high-affinity alpha-thrombin receptor had been removed by treatment with Serratia morcescens protease, In intact platelets, cytoplasmic acidification reached a maximum within 2 minutes of 0.072 +/- 0.009 pH units at 0.3 nmol/L alpha-thrombin concentration (0.03 U/ml). Cytoplasmic pH values were higher at both lower and higher alpha-thrombin concentrations and were significantly (p = 0.018) higher at 2 nmol/L alpha-thrombin, which induced -0.037 +/- 0.013 pH units of acidification. Five nanomoles of alpha-thrombin, however, induced cytoplasmic alkalinization of + 0.027 +/-0.033 pH units. In platelets lacking the high-affinity receptor where there is a 10 to 20-fold reduction in sensitivity to alpha-thrombin, acidification reached a maximum of - 0.175 +/- 0.033 pH units at 2 nmol/L alpha-thrombin, but alkalinization was observed at 5 nmol/L (+ 0.038 +/- 0.025) and 10 nmol/L ( + 0.042 - 0.007) alpha-thrombin. These results show that the transition from acidification to alkalinization occurs in the same range of alpha-thrombin concentrations (2 to 5 nmol/L) in both preparations, despite the rightward shift in sensitivity caused by the absence of the high-affinity receptor. However, the maximum acidification reached in control platelets (-0.037 pH units at 2 nmol/L) was much less than the value obtained in platelets lacking the high-affinity receptor (-0.175 pH units at 2 nmol/L alpha-thrombin). These studies suggest that at relatively low concentrations (< 2 nmol/L), alpha-thrombin induces cytoplasmic acidification in both platelet preparations, whereas higher doses ( > 5 nmol/L) induce cytoplasmic alkalinization. The significance of these cytoplasmic pH changes remains to be elucidated.

引用

页码：662 / 667

页数：6

共 43 条

[41] YAMAMOTO N, 1991, BLOOD, V77, P1740
[42] ZAVOICO GB, 1988, J BIOL CHEM, V263, P9635
[43] ZAVOICO GB, 1986, J BIOL CHEM, V261, P3160

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