title: ATPase activity and calcium uptake of microsomes isolated from stomach smooth muscle after exposure to phospholipase C.
abstract: ATPase activity and Ca2+ uptake were examined in microsomal membrane fractions isolated from guinea pig stomach smooth muscle which had been exposed to phospholipase C (PLC). Basal Mg2+-ATPase, Na+, K+-ATPase and Ca2+, Mg2+-ATP activities were inhibited in a time dependent manner by PLC treatment. There was positive correlations between each of these ATPase activities and total phospholipid content of the microsomal fraction. Phosphotidylcholine restored Ca2+, Mg2+-ATPase activity of the microsomal fraction isolated from the tissue which had been treated with PLC for 30 min but not after 60 min. Ca2+ uptake in the presence of ATP by microsomal fraction from tissue treated with PLC for 60 min was significantly decreased. The results provide a cellular basis for the inhibitory effect of PLC on contractility of stomach smooth muscle.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008861:Microsomes / Q000201:enzymology*; D009130:Muscle, Smooth / Q000166:cytology*; D010740:Phospholipases / Q000494:pharmacology*; D013270:Stomach; D010738:Type C Phospholipases / Q000494:pharmacology*
chemical_list: D010740:Phospholipases; D010738:Type C Phospholipases; D000251:Adenosine Triphosphatases; D002118:Calcium