title: Estimation of intracellular [Ca2+] by nonlinear indicators. A quantitative analysis.
abstract: When spatial gradients of intracellular free [Ca2+] are present, intracellular calcium indicators that have a nonlinear response to [Ca2+] may yield an estimate of [Ca2+] that differs from the spatial average [Ca2+]. We present two rules that provide (a) general criteria to distinguish those classes of indicators that will yield an overestimate of spatial average [Ca2+] from those that will yield an underestimate, and (b) limits on the extent to which spatial average [Ca2+] might be over- or underestimated. These rules are used to interpret quantitatively the aequorin luminescence signals obtained from cardiac ventricular myocardium.
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000032:analysis*; D002118:Calcium / Q000032:analysis*; D007424:Intracellular Fluid / Q000032:analysis*; D008433:Mathematics; D008954:Models, Biological; D009206:Myocardium / Q000032:analysis*
chemical_list: D002118:Calcium