Microvillar components of light adaptation in blowflies.
Microvillar components of light adaptation in blowflies.
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DOI：
10.1085/jgp.95.5.891
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发表时间：
1990-05
影响因子：
3.8
通讯作者：
HAMDORF, K
中科院分区：
文献类型：
--
作者：
HOCHSTRATE, P;HAMDORF, K
利用细胞内记录技术和二次和三次闪光刺激分析了绿头苍蝇光感受器的光适应过程。适应强度增加的闪光导致光感受器的兴奋性逐渐降低，当细胞吸收3 × 10（6）个量子时，这种兴奋性暂时受到抑制。这种抑制通过随后施加强烈的测试闪光来证实，该测试闪光光激活了细胞中的10（8）个视觉色素分子中的相当大的一部分。暂时脱敏的时期被称为不应期。在10（-4）和10（-2）M的范围内，使受体细胞不应的刺激强度与细胞外钙浓度无关。在不应期（适应闪光后30-40 ms），细胞似乎被“保护”免受进一步的光适应，因为在此期间的光吸收不影响细胞兴奋性的恢复。计算表明，诱导受体不应性所需的量子激发次数刚好足以光激活横纹肌的每一个微绒毛。这种巧合导致了这样的假设，即受体细胞的不应性是由于个体微绒毛的不应性。相对较弱的适应闪光后的受体细胞的敏感性大大降低，可以占微绒毛变得难治性。这些结果的定量分析表明，光活化的微绒毛诱导局部适应在一个相对较小的区域的横纹肌周围，其中包括几十个微绒毛。经过强烈的闪光灯的光适应，光活化的每一个微绒毛的吸收的几个量子产生的只有一个小的受体反应，而光活化的每一个视紫红质分子在每一个微绒毛产生的最大响应。因此，微绒毛的兴奋效率随着同时吸收的量子数而增加。
The process of light adaptation in blowfly photoreceptors was analyzed using intracellular recording techniques and double and triple flash stimuli. Adapting flashes of increasing intensity caused a progressive reduction in the excitability of the photoreceptors, which became temporarily suppressed when 3 x 10(6) quanta were absorbed by the cell. This suppression was confirmed by subsequently applying an intense test flash that photoactivated a considerable fraction of the 10(8) visual pigment molecules in the cell. The period of temporary desensitization is referred to as the refractory period. The stimulus intensity to render the receptor cell refractory was found to be independent of the extracellular calcium concentration over a range of 10(-4) and 10(-2) M. During the refractory period (30-40 ms after the adapting flash) the cell appears to be "protected" against further light adaptation since light absorption during this period did not affect the recovery of the cell's excitability. Calculations showed that the number of quantum absorptions necessary to induce receptor refractoriness is just sufficient to photoactivate every microvillus of the rhabdomere. This coincidence led to the hypothesis that the refractoriness of the receptor cells is due to the refractoriness of the individual microvilli. The sensitivity of the receptor cells after relatively weak adapting flashes was reduced considerably more than could be accounted for by the microvilli becoming refractory. A quantitative analysis of these results suggests that a photoactivated microvillus induces a local adaptation over a relatively small area of the rhabdomere around it, which includes several tens of microvilli. After light adaptation with an intense flash, photoactivation of every microvillus by the absorption of a few quanta produced only a small receptor response whereas photoactivation of every rhodopsin molecule in every microvillus produced the maximum response. The excitatory efficiency of the microvilli therefore increases with the number of quanta that are absorbed simultaneously.
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DOI：
10.1073/pnas.82.20.7116
发表时间：
1985-01-01
影响因子：
11.1
作者：
BLUMENFELD, A;ERUSALIMSKY, J;MINKE, B
通讯作者：
MINKE, B
影响因子：
5.5
作者：
BROWN, JE;BROWN, PK;PINTO, LH
通讯作者：
PINTO, LH
DOI：
10.1073/pnas.84.19.6939
发表时间：
1987-10-01
影响因子：
11.1
作者：
DEVARY, O;HEICHAL, O;SELINGER, Z
通讯作者：
SELINGER, Z
影响因子：
3.6
作者：
ELGAMMAL, S;HAMDORF, K;HENNING, U
通讯作者：
HENNING, U
DOI：
10.1007/bf00693635
发表时间：
1972-01-01
期刊：
JOURNAL OF COMPARATIVE PHYSIOLOGY
影响因子：
--
作者：
DORRSCHEIDTKAFER, M
通讯作者：
DORRSCHEIDTKAFER, M