RESUMEN
In cerebral arteries, alterations of vascular reactivity have been observed but not well molecularly characterized. Therefore, we have hypothesized that cerebrovascular reactivity could be modified by aging via a modification of Ca(2+) signaling in smooth muscle cells. Ca(2+) signals and gene expression implicated in contraction have been measured in posterior and middle cerebral arteries from young (2-3 months) and old (20-22 months) C57Bl6/J mice. Aging induced a decrease of KCl- and caffeine-induced contraction as well as a decrease of the amplitudes and an increase of the durations of KCl- and caffeine-induced Ca(2+) signals. These results could be linked with the decrease of gene expression coding for Cav1.2, RyR2, SERCA2, PLB, STIM1, TRIC-B, and the increase of FKBP12.6 and TPCN1 gene expression. Finally, aging induced a modification of InsP3 subtype expression pattern responsible for a modification of the InsP3 affinity to activate Ca(2+) signals. These results show that aging induces a decrease of contractility correlated with modifications of the expression of genes encoding Ca(2+) signaling toolkit. Globally, the amplitude of Ca(2+) signals was decreased, whereas their duration was increased by a defection of Ca(2+) store refilling.
