EFFECTS OF INOSITOL 1,4,5-TRISPHOSPHATE ON CALCIUM RELEASE FROM THE ENDOPLASMIC-RETICULUM AND GOLGI-APPARATUS IN MOUSE MAMMARY EPITHELIAL-CELLS - A COMPARISON DURING PREGNANCY AND LACTATION

It has been established that inositol 1,4,5‐trisphosphate(IP3) is responsible for the mobilization of calcium(Ca2+) from intracellular locations in a wide variety of tissues, and that this response triggers the stimulation of several hormones and neurotransmitters. However, these phenomena have yet to be examined in the mammary epithelium. Ca2+ uptake from the medium into the endoplasmic reticulum(ER) and Golgi apparatus in vitro in both pregnant and lactating mouse mammary epithelial cells was studied and a strong Ca2+ release from these organelles into the medium with the use of IP3 was shown. The Ca2+ uptake and its release due to IP3 was also usually greater during pregnancy than lactation. Copyright © 1990 John Wiley & Sons Ltd.