Ritodrine inhibition of the plasma membrane Ca2+-ATPase from human erythrocyte.

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Plenge-Tellechea F, Soler F, Fernandez-Belda F

Ritodrine inhibition of the plasma membrane Ca2+-ATPase from human erythrocyte.

Arch Biochem Biophys. 1998 Sep 15;357(2):179-84. doi: 10.1006/abbi.1998.0812.

PubMed ID

9735158 [ View in PubMed

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Abstract

The Ca(2+)-ATPase activity of human erythrocyte membrane can be inhibited in vitro by ritodrine, a beta 2-adrenergic agonist. The inhibitory profile shows a low-affinity interaction and no competition with the specific transport and catalytic substrates. The activated conformation of the enzyme (in the presence of calmodulin or after trypsin digestion) facilitates the interaction with ritodrine. This suggests that the C-terminal tail of the enzyme plays a protective role. By studying selected partial reactions of the catalytic and transport cycle we found that the inhibition can be basically assigned to a lower rate of phosphorylation by ATP. A minor effect on the phosphorylation level by Pi in the absence of Ca2+ and no effect on the enzyme affinity for Ca2+ or ATP were also observed. The inhibition of the plasma membrane Ca(2+)-ATPase by ritodrine shows a clear similarity with that of the sarcoplasmic/endoplasmic reticulum membrane. The inhibition under study does not foresee a pharmacological effect of ritodrine on the myometrial plasma membrane Ca(2+)-ATPase when administered for the management of preterm labor.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Ritodrine	Beta adrenergic receptor (Protein Group)	Protein group	Humans	Yes	Agonist Downregulator	Details
Ritodrine	Calcium transporting ATPases (Protein Group)	Protein group	Humans	Unknown	Inhibitor	Details