Liver plasma membrane enzyme activities following glutaraldehyde fixation

Area of Science:

• Biochemistry
• Histochemistry
• Cell Biology

Background:

• The Wachstein-Meisel ATPase histochemical method is used for enzyme localization.
• Previous studies utilized this method on liver and plasma membranes after glutaraldehyde fixation.

Purpose of the Study:

• To evaluate the reliability of the Wachstein-Meisel method for histochemical localization of Mg2+-ATPase and (Na+-K+)-ATPase in biliary canaliculi.
• To assess the impact of glutaraldehyde fixation on enzyme activity in liver plasma membranes.

Main Methods:

• Biochemical assays of liver plasma membrane enzymes after fixation in cold 2.5% glutaraldehyde.
• Histochemical application of the Wachstein-Meisel method to biliary canaliculi.

Main Results:

• Glutaraldehyde fixation preserved approximately 40% of Mg2+-ATPase activity but only 4% of (Na+-K+)-ATPase activity in liver plasma membranes.
• 5'-nucleotidase activity was nearly abolished by fixation.
• The Wachstein-Meisel method reliably localized Mg2+-ATPase but not (Na+-K+)-ATPase in biliary canaliculi.

Conclusions:

• The Wachstein-Meisel method is suitable for ultrastructural, histochemical localization of Mg2+-ATPase in biliary canaliculi.
• The method is not reliable for (Na+-K+)-ATPase localization due to fixation-induced activity loss.
• This method allows for comparative analysis of Mg2+-ATPase activity in normal versus chemically damaged biliary canaliculi.