title: Improved resolution of the initial fast phase of heavy sarcoplasmic reticulum Ca2+ uptake by Ca2+:antipyrylazo III dual-wavelength spectroscopy.
abstract: The effect of ATP upon difference absorbance due to Ca2+ and Mg2+ complexation with the metallochromic dye, Antipyrylazo III (AP III), was investigated. At divalent cation concentrations appropriate for Sarcoplasmic Reticulum Ca2+ transport, wavelengths (greater than 670 nm) were found whereupon the addition of up to 1mM nucleotide did not alter divalent cation:AP III difference absorbance. At these sample wavelengths an initial rapid uptake of Ca2+ by Heavy SR (HSR) was clearly resolved by dual wavelength spectroscopy of Ca2+:dye difference absorbance. Elimination of ATP interference of Ca2+:AP III absorbance by Mg2+ elevation (3-10mM) was shown to be an inappropriate general strategy for AP III spectroscopic studies of HSR Ca2+ transport due to Mg2+ inhibition of ryanodine receptor mediated Ca2+ release.
authors.affiliation: Faculty of Graduate Studies, University of British Columbia, Vancouver, Canada.
authors.forename: J S
authors.initials: JS
authors.lastname: Gilchrist
authors.forename: S
authors.initials: S
authors.lastname: Katz
authors.forename: A N
authors.initials: AN
authors.lastname: Belcastro
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009282:Naphthalenesulfonates; D011794:Quercetin / Q000494:pharmacology; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D002413:Cations, Divalent; D009282:Naphthalenesulfonates; D000001:Calcimycin; D000255:Adenosine Triphosphate; D011794:Quercetin; C016238:antipyrylazo III; D008274:Magnesium; D002118:Calcium