Influence of heat stress on calcium currents of drosophila presenilin mutants

The linkage between presenilin induced mutations and the pathogenesis of early-onset familial Alzheirner's disease was analyzed by studying other presenilin functions in addition to the cleavage of APP (amyloid precursor protein). The calcium and potassium currents in drosophila larva body wall muscle were recorded using the two electrode voltage clamp method. The results show that calcium currents are not affected by either normal or heat shock treatments. However, after heat shock creatments, the calcium tail currents in the mutant flies were much slower. These results indicate that presenilin is not required for maintaining Ca²⁺ channel functions during either normal or stressed conditions, but is involved after the stress is removed. Presenilin is critical for maintaining Ca²⁺ channels during post stress periods and, therefore, is critical for maintaining calcium homeostasis in a fluctuating environment.