Monday, August 07, 2006

Some Cell Membrane Stuff

This week's theme is about cell membranes and the proteins in them, and that is what our PSS today was about. We had to read an article for today's session about how excess cholesterol, besides causing atherosclerosis, can also cause heart problems due to there being too much cholesterol in the heart cell membranes. This is a problem because cholesterol affects the fluidity of the membranes and makes them less fluid at physiological concentrations. Apparently that stiffening of the membrane leads to all kinds of other problems, like with ion channels and other membrane proteins not being able to change their conformations like they're supposed to do.

Tomorrow, we are seeing our first patient, and he has an arrythmia. Presumably it's due to a potassium channel problem, because we had a 56-page review article to read for tomorrow about all these different channelopathies, and that was one of the channel diseases that it mentioned. In college you learn about potassium channels and sodium channels and how they are responsible for action potentials in neurons. But there are also calcium channels and chloride channels that can cause diseases if they aren't working properly, and then there are several subtypes of each, as well as other channels that aren't specific for a single ion. Some channels are expressed in certain tissues and not in others; some are voltage-gated while others are ligand-gated or voltage-insensitive; some activate or inactivate slower or faster than others do. It's kind of mind-blowing to read about them all.

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