A decrease in plasma Ca2+ and increases in plasma immunoreactive parathyroid hormone (PTH) have been reported in spontaneously hypertensive (SH) rats as compared with normotensive Wistar-Kyoto (WKy) rats. These changes should lead to a higher plasma 1,25(OH)2D (1,25-dihydroxycholecalciferol/1,25-dihydroxyergocalciferol) concentration in SH rat if the kidney responds appropriately. Plasma 1,25(O...

Osteoporosis remains a challenging problem. Understanding the regulation on osteoclast and osteoblast by drugs has been of great interest. Both anabolic and anti-resorptive drugs yield positive results in the treatment of osteoporosis. However, whether the concurrent administration of parathyroid hormone (1-34) and ibandronate may offer an advantage over monotherapy is still unknown. This study...

Parathyroid hormone (PTH, less than 10(-8) M) stimulated adenylate cyclase in fibroblasts, but not epithelial cells, isolated from fetal rat lung. In contrast to osteosarcoma cells (UMR 106), the response of fibroblasts to PTH was increased by pretreatment with cortisol (less than 10(-8)-10(-7) M).

Interleukin-6 (IL-6) is an important mediator of parathyroid hormone (PTH)-induced bone resorption. Serum levels of IL-6 and its soluble receptor (IL-6sR) are regulated in part by PTH. The PTH/PTH-related protein type 1 receptor is highly expressed in the liver, and in the current study we investigated whether the liver produces IL-6 or IL-6sR in response to PTH. Perfusion of the isolated rat l...

Parathyroid hormone (PTH) and mechanical stress both stimulate bone formation but have opposite effects on bone resorption. PTH increased loading-induced bone formation in a rat model, suggesting that there is an interaction of these stimuli, possibly at the cellular level. To investigate whether PTH can modulate mechanotransduction by bone cells, we examined the effect of 10-9 M human PTH-(1-3...

Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) target the kidney to cause a phosphaturia. FGF23 also acts on the parathyroid to decrease PTH expression, but in chronic kidney disease (CKD) there are high-serum PTH and FGF23 levels and resistance of the parathyroid to FGF23. We now report that PTH acts on bone to increase FGF23 expression and characterize the signal transducti...

This study aims to investigate the effects of two application frequencies of parathyroid hormone on the trochanteric region of rat femur. Forty-three-month-old female Sprague-Dawley rats were divided into 4 groups (n = 10/group). Three groups were ovariectomized, and 8 weeks later they were administered the following treatments (5 weeks): soy-free diet (OVX), subcutaneously injected PTH (0.040 ...

Direct effects of parathyroid hormone (PTH) on calcium uptake by isolated rat duodenal cell preparations enriched in enterocytes were investigated. PTH significantly stimulated enterocyte45Ca2+influx in a time-dependent (1-10 min) manner and at all doses tested (2 × 10-13 to 10-7 M). The Ca2+ channel antagonists verapamil (10 μM) and nitrendipine (1 μM) completely blocked the stimulation of Ca2...

We examined two inhibitors of DNA synthesis, hydroxyurea (HU) and aphidicholin (APC), and two inhibitors of prostaglandin cyclooxygenase, indomethacin and flufenamic acid, for their effects on the resorptive responses of fetal rat long-bone cultures to epidermal growth factor (EGF) and parathyroid hormone (PTH). As we have previously found, HU decreased unstimulated 45Ca release but had little ...

This study asks whether arterial blood ionized calcium concentration (Ca++) can regulate the serum level of 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] independently of serum phosphorus and parathyroid hormone (PTH). We infused either PTH (bovine 1-34, 10 U/kg body wt/h) or saline into awake and unrestrained rats for 24 h, through a chronic indwelling catheter. PTH raised total serum calcium and ar...