The Effect of Parathyroid Hormone on the Uptake and Release of Calcium by Bone in Tissue Culture

Abstract

1. Bovine parathyroid hormone at a concentration of 1 unit/ml caused an immediate transient uptake of calcium from the bathing medium by 5-day-old mouse calvaria in tissue culture.2. The uptake of calcium by bone was followed by the release of calcium into the medium over the subsequent 3-4 h.3. The results support the conclusion that the primary action of the hormone on calcium transport in bone is to cause an increase in the intracellular concentration of calcium before producing the characteristic release of calcium from bone.

Parathyroid hormone is not a key hormone in the rapid minute‐to‐minute regulation of plasma Ca2+ homeostasis in rats

“…calvaria [24][25][26]. The recently demonstrated anabolic effect on bone of intermittent peak concentrations of PTH1-34 in contrast to the catabolic effect of long-term high PTH levels would be in agreement with this initial hypocalcaemic effect of PTH [27,28].…”

“…The time course of the release of calcium from the skeleton is controversial. An initial hypocalcaemic action of PTH, before resulting in hypercalcaemia, has been observed in vivo during the first 30 min after administration of bovine PTH1–34 to dogs and found in vitro in mouse calvaria [ 24–26]. The recently demonstrated anabolic effect on bone of intermittent peak concentrations of PTH1–34 in contrast to the catabolic effect of long‐term high PTH levels would be in agreement with this initial hypocalcaemic effect of PTH [ 27, 28].…”

Cyclic 3′,5′-Adenosine Monophosphate in Isolated Bone Cells. II. Responses to Adenosine and Parathyroid Hormone1

“…In addition, extracellular C a + + , which is required for the maximal generation of cyclic 3',5 / -AMP by depolarizing agents in brain, also appears to participate in the skeletal actions of PTH. PTH acutely lowers the serum C a + + concentration when administered to experimental animals and increases the accumulation of C a + + in isolated bone segments in vitro (21)(22)(23). The studies described herein reveal that adenosine rapidly, and in low concentrations, increases cyclic 3 / ,5 / -AMP levels in bone cells; and adenosine and PTH increase cyclic 3',5'-AMP synergistically.…”

Bone resorption in organ culture: inhibition by the divalent cation ionophores A23187 and X-537A.

“…Both in vivo (9) and in vitro (10,11) experiments have suggested that this decrease in plasma calcium is due to an accumulation of the ion in bone. These findings led Parsons and his co-workers to hypothesize that calcium uptake by bone is one of the earliest actions of PTH on this target tissue (8,9).…”