ELECTRON-PROBE MICROANALYSIS OF CALCIUM RELEASE AND MAGNESIUM UPTAKE BY ENDOPLASMIC-RETICULUM IN BEE PHOTORECEPTORS

被引:77
作者
BAUMANN, O
WALZ, B
SOMLYO, AV
SOMLYO, AP
机构
[1] UNIV VIRGINIA,MED CTR,DEPT PHYSIOL,BOX 449,CHARLOTTESVILLE,VA 22908
[2] UNIV REGENSBURG,INST ZOOL,W-8400 REGENSBURG,GERMANY
关键词
SIGNAL TRANSDUCTION; RETINA; INVERTEBRATES;
D O I
10.1073/pnas.88.3.741
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Honey bee photoreceptors contain large sacs of endoplasmic reticulum (ER) that can be located unequivocally in freeze-dried cryosections. The elemental composition of the ER was determined by electron probe x-ray microanalysis and was visualized in high-resolution x-ray maps. In the ER of dark-adapted photoreceptors, the Ca concentration was 47.5 +/- 1.1 mmol/kg (dry weight) (mean +/- SEM). During a 3-sec nonsaturating light stimulus, almost-equal-to 50% of the Ca content was released from the ER. Light stimulation also caused a highly significant increase in the Mg content of the ER; the ratio of Mg uptake to Ca released was almost-equal-to 0.7. Our results show unambiguously that the ER is the source of Ca2+ release during cell stimulation and suggest that Mg2+ can nearly balance the charge movement of Ca2+.
引用
收藏
页码:741 / 744
页数:4
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