The influence of calcium on lens ATPase activity.

The influence of calcium on the rabbit lens sodium pump.

PURPOSE Experiments were conducted to examine how elevation of calcium in the lens impairs the lens sodium pump. METHODS Rabbit lenses were incubated in the presence or absence of calcium ionophore A23187. 86Rb uptake by the intact lens was measured as an index of sodium pump activity. Na,K-ATPase (ouabain-sensitive adenosine triphosphate [ATP] hydrolysis) activity was determined in membrane ...

Ca-ATPase activity in the rabbit and bovine lens.

Membrane-rich vesicle preparations of rabbit and bovine lenses were prepared in such a manner as to preserve ATPase activity. The lipid:protein ratio of these preparations was increased 22- to 33-fold with a 94% recovery of total phospholipid. Using this preparation, calcium stimulated ATPase was routinely determined in both individual lenses and in pooled specimens. The pattern of stimulation ...

A Role for Calcium-Activated Adenylate Cyclase and Protein Kinase A in the Lens Src Family Kinase and Na,K-ATPase Response to Hyposmotic Stress.

Purpose Na,K-ATPase activity in lens epithelium is subject to control by Src family tyrosine kinases (SFKs). Previously we showed hyposmotic solution causes an SFK-dependent increase in Na,K-ATPase activity in the epithelium. Here we explored the role of cAMP in the signaling mechanism responsible for the SFK and Na,K-ATPase response. Methods Intact porcine lenses were exposed to hyposmotic K...

Regional distribution of Na,K-ATPase activity in porcine lens epithelium.

PURPOSE It has been established that Na,K-ATPase activity is higher in lens epithelium than fibers. However, others have suggested the Na,K-ATPase enzyme may be inactive or absent in the central 10% of the epithelium. Studies were conducted to measure and compare Na,K-ATPase specific activity and to examine Na,K-ATPase protein expression in the anterior and equatorial regions of porcine lens ep...

Influence of calcium and non-phytate phosphorus deficient diets with phytase on the performance of broilers, serum concentrations of minerals and the activity of alanin transaminase, aspartate transaminase and lactate dehydrogenas e