title: Oxalate-stimulation of ATP-dependent Ca-uptake is diminished during smooth muscle subcellular fractionation.
abstract: The ATP-dependent azide-insensitive Ca-uptake by the postnuclear supernatant from rat myometrium is stimulated more by 5 mM oxalate than by 25 mM phosphate. During subcellular fractionation, however, the percent recovery of the oxalate stimulated Ca-uptake diminishes more rapidly than that of the Ca-uptake without any added oxalate or phosphate. The percent recovery of the phosphate stimulated Ca-uptake also diminishes but not to as low levels as that of the oxalate stimulated Ca-uptake. The net result is higher stimulation of this uptake by 25 mM phosphate than by 5 mM oxalate in the various sucrose density gradient fractions. This discrepancy in percent recoveries presents a major concern about the use of oxalate or phosphate stimulated Ca-uptake as a marker for smooth muscle membranes.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002458:Cell Fractionation; D005260:Female; D009130:Muscle, Smooth / Q000166:cytology* / Q000378:metabolism; D009215:Myometrium / Q000166:cytology / Q000378:metabolism; D010070:Oxalates / Q000494:pharmacology*; D019815:Oxalic Acid; D010710:Phosphates / Q000494:pharmacology; D051381:Rats; D014018:Tissue Distribution
chemical_list: D010070:Oxalates; D010710:Phosphates; D000255:Adenosine Triphosphate; D019815:Oxalic Acid; D002118:Calcium