SARCOPLASMIC-CA-2+ TRANSIENTS DURING THE CONTRACTILE CYCLE OF SINGLE BARNACLE MUSCLE-FIBERS - MEASUREMENTS WITH ARSENAZO-III-INJECTED FIBERS
SARCOPLASMIC-CA-2+ TRANSIENTS DURING THE CONTRACTILE CYCLE OF SINGLE BARNACLE MUSCLE-FIBERS - MEASUREMENTS WITH ARSENAZO-III-INJECTED FIBERS
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DOI：
10.1007/bf00711882
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发表时间：
1982-01-01
影响因子：
2.7
通讯作者：
SCARPA, A
中科院分区：
文献类型：
--
作者：
DUBYAK, GR;SCARPA, A
来自B的单个肌纤维。nubilus注射金属铬钙2+指示剂偶氮胂III;多波长显微分光光度法被用来监测等长张力瞬变过程中引起的电刺激等纤维的吸收光谱的变化。在光谱的660-720-nm区域记录的微分吸光度变化的特征在于在恒定电流去极化脉冲（25-200 ms）期间快速、接近线性增加;在电刺激终止时，增加的微分吸光度描述了向基线水平的指数（k = 0.6-2.0 s-1）衰减。在15 - 17 ℃，这些吸光度信号的最大增加先于张力瞬变峰值300-400 ms。C.这些光学瞬变的校准表明上升相的初始速度对应于肌浆游离Ca 2+的0.03 μ M ms-1增加。直到游离Ca 2+瞬变的表观峰值幅度超过2 μ M才产生可感知的张力;游离Ca 2+瞬变的最大值的进一步3倍增加（从2至6 μ M）伴随着张力瞬变幅度的20倍增加。
Single muscle fibers from B. nubilus were injected with the metallochromic Ca2+ indicator arsenazo III; multi-wavelength microspectrophotometry was used to monitor changes in the absorption spectrum of such fibers during isometric tension transients elicited by electrical stimulation. Differential absorbance changes, recorded in the 660-720-nm region of the spectrum, were characterized by rapid, nearly linear increases during constant current depolarizing pulses (25-200 ms); upon termination of electrical stimuli, the increased differential absorbance described an exponential (k = 0.6-2.0 s-1) decay toward baseline levels. The maximal increases in these absorbance signals preceded the peaks of the tension transients by 300-400 ms at 15-17.degree. C. Calibration of these optical transients indicated that the initial velocity of the rising phase corresponded to a 0.03 .mu.M ms-1 increase in sarcoplasmic free Ca2+. Appreciable tension was not generated until the apparent peak magnitude of the free Ca2+ transient exceeded 2 .mu.M; a further 3-fold increase (from 2 to 6 .mu.M) in the maximal value of the free Ca2+ transient was accompanied by a 20-fold increase in the magnitude of the tension transient.