Effects of Lanthanum on 45Ca Movements and Oxytocin-Induced Milk Ejection in Mammary Tissue:

SummaryLanthanum did not cause an expected increase in the efflux of 45Ca from mammary tissue. The presence of nonradioactive calcium in the media probably precluded such movement. However, lanthanum did significantly reduce the milk ejection response of mammary tissue to oxytocin. The nature of this reduction indicates that a superficial calcium pool plays a role in myoepithelial cell contraction. Evidence in this report does not strongly favor any direct movement of extracellular calcium into the myoepithelial cell after oxytocin treatment.