Electrochemical analysis of cell plasma membrane cholesterol at the airway surface of mouse trachea.

Electrochemical detection of plasma membrane cholesterol at the surface of excised mouse trachea tissue is reported. Cholesterol oxidase is covalently linked to an 11-mercaptoundecanoic acid submonolayer on the platinum electrode surface. The cholesterol oxidase-modified electrodes show steady-state responses for cholesterol in solution at physiological temperatures. Experiments for direct contact between the cholesterol oxidase-modified electrode and the surface of excised trachea tissue at 37 degrees C indicate steady-state responses that are largely independent of the position of contact on the tissue surface. Tissue samples are mounted on a quartz crystal microbalance electrode to gauge contact force between the electrode and the tissue surface, and the steady-state electrode response for tissue cholesterol is shown to be largely independent of the contact force. Trachea tissue excised from a mouse model of cystic fibrosis, which is known to exhibit evaluated cholesterol in airway cells, shows an electrode response that is approximately 40% larger than the response observed at wild-type mouse trachea tissue.