Calcium uptake and calcium release by subcellular fractions of smooth muscle. II. Kinetics of calcium uptake by microsomes and mitochondria from pig coronary artery and guinea pig ileum.
Calcium uptake by the microsomal and mitochondrial fractions of pig coronary artery and guinea pig ileum was studied in the presence of ATP, ATP plus oxalate and without ATP and oxalate. Microsomes and mitochondria of both smooth muscles were found to be unable to accumulate appreciable amounts of calcium in the absence of ATP. Oxalate noticeably stimulated the calcium uptake of the mitochondrial fraction from pig coronary artery but had little effect on calcium uptake by the microsomal fraction of this smooth muscle. The calcium uptake of microsomes and mitochondria from guinea pig ileum was not or only slightly enhanced by oxalate. There are typical kinetics regarding the time course and the extent of calcium uptake by microsomes and mitochondria from pig coronary artery and guinea pig ileum. In comparison, considerable qualitative and quantitative differences between both smooth muscles are observed. The high ATP-dependent calcium uptake capacity of the mitochondria from pig coronary artery and guinea pig ileum are a further argument for the hypothesis that these organelles may play an important role in the contraction-relaxation mechanism of smooth muscle.
D000255:Adenosine Triphosphate; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003331:Coronary Vessels; D006168:Guinea Pigs; D007082:Ileum; D007700:Kinetics; D008861:Microsomes / Q000378:metabolism*; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000378:metabolism*; D010070:Oxalates; D013552:Swine
D010070:Oxalates; D000255:Adenosine Triphosphate; D002118:Calcium