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Measurement of shear stress-mediated intracellular calcium dynamics in human dermal lymphatic endothelial cells.

Jafarnejad M, Cromer WE, Kaunas RR, Zhang SL, Zawieja DC, Moore JE - Am. J. Physiol. Heart Circ. Physiol. (2015)

Bottom Line: Removal of the extracellular calcium from the buffer or pharmocological blockade of calcium release-activated calcium (CRAC) channels significantly reduced the peak [Ca(2+)]i, demonstrating a role of extracellular calcium entry.Inhibition of endoplasmic reticulum (ER) calcium pumps showed the importance of intracellular calcium stores in the initiation of this signal.In conclusion, we demonstrated that the shear-mediated calcium signal is dependent on the magnitude of the shear and involves ER store calcium release and extracellular calcium entry.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, Imperial College, London, England;

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Curve-fit to the upstroke and downstroke of the calcium spike. The 1st peak of the calcium response to 10 dyn/cm2 shear stress is shown with filled circles (●; means ± SE; n = 9). A sample linear fit of the form ratio = a1 × t + a2 to the upstroke (the red line) and a sample exponential fit of the form ratio = b1 × exp[(t − t0)/b2] + b3 to the downstroke (the blue curve) are shown in this figure. a1 and b2 are the main parameters that are reported in the Table 1.
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Figure 6: Curve-fit to the upstroke and downstroke of the calcium spike. The 1st peak of the calcium response to 10 dyn/cm2 shear stress is shown with filled circles (●; means ± SE; n = 9). A sample linear fit of the form ratio = a1 × t + a2 to the upstroke (the red line) and a sample exponential fit of the form ratio = b1 × exp[(t − t0)/b2] + b3 to the downstroke (the blue curve) are shown in this figure. a1 and b2 are the main parameters that are reported in the Table 1.

Mentions: The calcium responses to shear were fit to mathematical function to extract parameters for subsequent modeling efforts (Fig. 6). The [Ca2+]i increased rapidly to reach a peak value, which was approximated using a linear function in the form of ratio = a1 × t + a2 (Fig. 6, red line). The gradual drop in signal suggested an exponential fit {ratio = b1 × exp[(t − t0)/b2] + b3} as an adequate approximation for this part of the response (Fig. 6, blue curve). Among the curve-fitting parameters, the upstroke slope showing the [Ca2+]i increase rate (a1) and the downstroke time constant (b2) are the most important parameters and are reported for the various cases tested in this study for the first and second peaks (Table 1). When the shear stress increased from 1 to 10 dyn/cm2 in the absence of inhibitors, the upstroke slope increased sixfold for the first peak suggesting a faster increase in the signal, and the downstroke time constant decreased from 4.6 to 3.0 min meaning that the signal dropped faster when the shear stress was higher (Table 1).


Measurement of shear stress-mediated intracellular calcium dynamics in human dermal lymphatic endothelial cells.

Jafarnejad M, Cromer WE, Kaunas RR, Zhang SL, Zawieja DC, Moore JE - Am. J. Physiol. Heart Circ. Physiol. (2015)

Curve-fit to the upstroke and downstroke of the calcium spike. The 1st peak of the calcium response to 10 dyn/cm2 shear stress is shown with filled circles (●; means ± SE; n = 9). A sample linear fit of the form ratio = a1 × t + a2 to the upstroke (the red line) and a sample exponential fit of the form ratio = b1 × exp[(t − t0)/b2] + b3 to the downstroke (the blue curve) are shown in this figure. a1 and b2 are the main parameters that are reported in the Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385995&req=5

Figure 6: Curve-fit to the upstroke and downstroke of the calcium spike. The 1st peak of the calcium response to 10 dyn/cm2 shear stress is shown with filled circles (●; means ± SE; n = 9). A sample linear fit of the form ratio = a1 × t + a2 to the upstroke (the red line) and a sample exponential fit of the form ratio = b1 × exp[(t − t0)/b2] + b3 to the downstroke (the blue curve) are shown in this figure. a1 and b2 are the main parameters that are reported in the Table 1.
Mentions: The calcium responses to shear were fit to mathematical function to extract parameters for subsequent modeling efforts (Fig. 6). The [Ca2+]i increased rapidly to reach a peak value, which was approximated using a linear function in the form of ratio = a1 × t + a2 (Fig. 6, red line). The gradual drop in signal suggested an exponential fit {ratio = b1 × exp[(t − t0)/b2] + b3} as an adequate approximation for this part of the response (Fig. 6, blue curve). Among the curve-fitting parameters, the upstroke slope showing the [Ca2+]i increase rate (a1) and the downstroke time constant (b2) are the most important parameters and are reported for the various cases tested in this study for the first and second peaks (Table 1). When the shear stress increased from 1 to 10 dyn/cm2 in the absence of inhibitors, the upstroke slope increased sixfold for the first peak suggesting a faster increase in the signal, and the downstroke time constant decreased from 4.6 to 3.0 min meaning that the signal dropped faster when the shear stress was higher (Table 1).

Bottom Line: Removal of the extracellular calcium from the buffer or pharmocological blockade of calcium release-activated calcium (CRAC) channels significantly reduced the peak [Ca(2+)]i, demonstrating a role of extracellular calcium entry.Inhibition of endoplasmic reticulum (ER) calcium pumps showed the importance of intracellular calcium stores in the initiation of this signal.In conclusion, we demonstrated that the shear-mediated calcium signal is dependent on the magnitude of the shear and involves ER store calcium release and extracellular calcium entry.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, Imperial College, London, England;

Show MeSH
Related in: MedlinePlus