Erythrocyte cytosolic free Ca2+ and plasma membrane Ca2+-ATPase activity in cystic fibrosis

Cell Calcium
R L WallerD G Dearborn

Abstract

The properties of the Ca2+, Mg2+-ATPase of erythrocyte membranes from patients with cystic fibrosis (CF) were extensively compared to that of healthy controls. Following removal of an endogenous membrane inhibitor of the ATPase, activation of the enzyme by Ca2+, calmodulin, limited tryptic digestion or oleic acid, as well as inhibition by trifluoperazine, were studied. The only properties found to be significantly different (CF cells vs controls) were calmodulin-stimulated peak activity (90 vs 101, P less than 0.02) and trypsin-activated peak activity (92 vs 102, P less than 0.02). No significant difference could be measured in the steady-state Ca2+-dependent phosphorylation of CF and control erythrocyte membranes indicating similar numbers of enzyme molecules per cell. The functional state of Ca2+ homeostasis in intact erythrocytes was investigated by measuring the resting cytosolic free Ca2+ levels using quin-2. Both CF and control erythrocytes maintained cytosolic free Ca2+ between 20 to 30 nM. Addition of 50 uM trifluoperazine resulted in an increase in erythrocyte cytosolic free Ca2+ to about 50 nM in both CF and control cells. Estimates of erythrocyte membrane permeability using the steady-state uptake of 45Ca into intact...Continue Reading

Citations

Sep 1, 1993·Journal of Fluorescence·H SzmacinskiM L Johnson
Feb 1, 1992·Molecular and Biochemical Parasitology·N McCallum-Deighton, A A Holder
Dec 31, 1990·Biochemical and Biophysical Research Communications·M David-DufilhoM A Devynck
May 29, 1987·Biochimica Et Biophysica Acta·G Dagher
Feb 1, 1992·Hypertension·M David-DufilhoM A Devynck
Jan 1, 1988·Acta Medica Scandinavica·G Ronquist, G Frithz

Related Concepts

Ca(2+)-Transporting ATPase
Calcium
Cyclic AMP-Phosphodiesterase Activator
Pulmonary Cystic Fibrosis
Cytoplasmic Matrix
Red Cell Ghost
Erythrocytes
Oleic Acids
Apo-Trifluoperazine

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