Developmental changes in capacitative Ca2+ entry in mouse mammary epithelial cells

Developmental changes in capacitative Ca2+ entry and Ca2+ release from intr acellular stores were measured using fura-2 fluorescence method during the pregnancy period (day 3-18) in mouse mammary epithelial cells. Ca2+ release was identified with the transient intracellular Ca2+ ([Ca2+](i)) increase induced by thapsigargin addition in a Ca2+-free solution. Capacitative Ca2 entry was measured by the transient [Ca2+](i) increase induced by re-addit ion of extracellular Ca2+ after depiction of Ca2+ stores by thapsigargin. T he capacitative Ca2+ entry was greatest at the early stage of pregnancy (i. e. day 3 of pregnancy) and decreased as pregnancy progressed, while Ca2+ re lease remained unchanged throughout the developmental stages. These finding s indicate that in contrast to Ca2+ release, a close correlation exists bet ween capacitative Ca2+. entry and pregnancy-induced development in mammary epithelial cells. Copyright (C) 2000 John Wiley & Sons, Ltd.