INVOLVEMENT OF CA-2+-INDUCED CA-2+ RELEASE IN THE VOLUME REGULATION OF HUMAN EPITHELIAL-CELLS EXPOSED TO A HYPOTONIC MEDIUM

被引:51
作者
HAZAMA, A [1 ]
OKADA, Y [1 ]
机构
[1] KYOTO UNIV,FAC MED,DEPT PHYSIOL,SAKYO KU,KYOTO 606,JAPAN
关键词
D O I
10.1016/0006-291X(90)91763-I
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Exposure of cultured human epithelial cells (Intestine 407) to a hypotonic solution results in initial osmotic swelling and in a subsequent volume decrease near to the original level. The regulatory volume decrease was inhibited by reduction of the extracellular free Ca2+ concentration to 90 nM. Single epithelial cells responded to a hypotonic challenge with a biphasic increase in the cytosolic free Ca2+ level from about 90 to 200 nM. Both phases of the Ca2+ rise were abolished by reducing the extracellular Ca2+ to 90 nM. In the presence of caffeine (20 mM), the second-phase Ca2+ response to a hypotonic challenge occurred earlier immediately after the first-phase response. The second-phase Ca2+ response was selectively impaired by adenine (10 mM), procaine (1 mM) or ryanodine (5 to 10 μM). These blockers for Ca2+-induced Ca2+ release channels inhibited volume regulation after osmotic swelling. It is concluded that Ca2+-induced Ca2+ release from a ryanodine-sensitive store is a prerequisite for the volume regulation of human intestinal epithelial cells under hypotonic conditions. © 1990.
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页码:287 / 293
页数:7
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