Secretion of parathyroid hormone-related protein by bovine mammary cells in vitro

Mammary cells were isolated from lactating cows at 1 to 6 weeks after calving and evaluated for their ability to secrete PTHrP in vitro. The tissue was enzymatically digested to release glandular acini. The digested acini were cultured on thin (1.0 mm) or thick (2.5 mm) layers of collagen. The cultures containing thick collagen were detached and allowed to contract on day 6. The culture medium consisted of M199 with prolation (8 µg/ml), insulin (5 µg/ml), cortisol (5 µg/ml), and fetal bovine serum (15%). PTHrP production was measured by N-terminal RIA and bioassay (stimulation of adenylate cyclase in the ROS 17/2.8 cell line). Medium was collected at 2-day intervals for 14 days. The cells reached confluence at 4–6 days. PTHrP production was low at day 2 (<0.5 ng/ml), but increased to peak production (2–4 ng/ml) at approximately day 6–8 of culture and remained constant until day 14. Immunoreactive and bioactive PTHrP levels in the culture medium correlated well. The cultures produced high levels of lactoferrin (500 to 3000 ng/ml) and low levels of α s1 -casein (14 to 77 ng/ml).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41592/1/774_2006_Article_BF02375695.pd

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Evidence that Parathyroid Hormone-mediated Calcium Transport in Rat Brain Synaptosomes Is Independent of Cyclic Adenosine Monophosphate

In vivo PTH administration to rats resulted in increased brain synaptosomal Ca++ transport, while parathyroidectomy (PTX) resulted in decreased transport. To determine the mechanism of action of PTH on Ca++ transport in rat brain synaptosomes, we performed transport studies by the Na-Ca exchanger and also measured cAMP generation in synaptosomes from PTX rats. Ca++ transport was studied after in vivo additions of either bovine (b)PTH, cAMP, or forskolin, and adenylate cyclase activity was assessed after additions of either bPTH, forskolin, sodium fluoride (NaF), or isoproterenol. In the presence of 1-34 bPTH 110-7 MI, Ca++ uptake was significantly increased by 55 % (P &lt; 0.001) above control, while 3-34 bPTH 110 &apos; Ml had no effect on uptake. Both 8br,cAMP [10 &apos; MN and dibut,cAMP [10 &apos; Ml also significantly increased (