TETRAETHYLAMMONIUM-INDUCED CALCIUM-CONCENTRATION CHANGES IN SKIN FIBROBLASTS FROM PATIENTS WITH ALZHEIMER-DISEASE

Potassium (Kc) channel dysfunction in fibroblasts was recently propose d as a potential diagnostic marker for Alzheimer disease (AD), We util ized a microspectrofluorometric method with Fura-2AM to measure intrac ellular free calcium ([Ca2+](i)) following depolarization with the Kchannel blocker tetraethylammonium (TEA) in seven AD and seven control fibroblast cultures, Contrary to our expectation, 43% of the AD and 3 6% of the control fibroblast plated coverglasses responded with an inc rease in [Ca2+](i) on addition of 100 mM TEA. The data suggest that th e TEA-elicited [Ca2+](i) response is not a useful AD screening test.