Developmental and age-related alterations of calcium homeostasis in human fibroblasts

Calcium homeostasis, in terms of both cytosolic calcium concentration ([Ca(2+)](i)) and capacitative calcium entry, has been investigated in human skin and lung fibroblasts at different developmental and ageing stages by employing the Fura-2 based measurements. [Ca(2+)](i) in foetal lung or skin cells were nearly similar. However, significant changes were observed between foetal and adult fibroblasts and interestingly in opposite directions depending on the tissue of origin. In particular, in adult lung cells [Ca(2+)](i) was more than three-fold higher compared to adult skin fibroblasts, a difference which may contribute to tissue-specific functions. Capacitative Ca(2+) entry, i.e. the transient [Ca(2+)](i) increase induced by re-addition of extracellular calcium after depletion of thapsigargin-sensitive calcium stores, was found to exhibit the same pattern of differences during foetal-to-adult transition (it is two-fold higher in adult lung cells than in adult skin cells). At variance, we found capacitative Ca(2+) entry to be significantly attenuated during in vivo or in vitro ageing of fibroblasts; while minor alterations of [Ca(2+)](i) were observed. These findings indicate that capacitative calcium entry rather than [Ca(2+)](i), is mainly affected during the ageing process.