Effects of prostaglandin E1 on the metabolism in rat parathyroid gland in vitro.

We investigated some effects of prostaglandin E1 on the metabolism of rat parathyroid glands using a culture system containing basal Eagle's medium supplemented with 5--10% heat-inactivated rat serum. Rat parathyroid glands incorporate [3H]fucose and 14C-labeled amino acids into cellular glycoproteins and secrete some of these into the culture medium. Gel filtration chromatography separates these glycoproteins into three classes, the smallest of which (peak 3) is secreted with immunoreactive parathyroid hormone. In cultures of 48 h, prostaglandin E1 (1 microgram/ml) specifically inhibits the secretion of peak 3 and of parathyroid hormone but has no effect on the incorporation of [3H]fucose, 14C-labeled amino acids, or [3H]uridine into parathyroid glands. Cytochalasin B inhibits the secretion of parathyroid hormone and the incorporation of isotopic fucose and amino acids. Cortisol stimulates incorporation of [3H]fucose and the secretion of parathyroid hormone even in the presence of inhibitory doses of prostaglandin E1. It is concluded that, in organ culture, prostaglandin E1 inhibits the secretion of parathyroid hormone and of a specific glycoprotein the function of which may be related to the secretion of the hormone.