Ricardo L. Boland

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25-hydroxycholecalciferol (25OHD3) and 1,25-dihydroxycholecalciferol (1,25(OH)2D3) at physiological concentrations exerted direct effects on Ca fluxes in cultured vitamin D-deficient chick soleus muscle and myoblasts. Isotopic desaturation curves of soleus muscle prelabeled with45Ca indicated that the action of 25OHD3 is localized in a slow-exchangeable Ca(More)
There is evidence that extracellular nucleotides, acting through multiple P2 receptors, may play an important role in the regulation of bone metabolism by activating intracellular signaling cascades. We have studied the modulation of mitogen-activated protein kinase (MAPK) signaling pathways and its relationship to changes in intracellular calcium(More)
In ROS 17/2.8 rat osteoblastic-like cells a capacitative Ca(2+) entry (CCE) pathway operates which is activated by either 1alpha,25-dihydroxy-vitamin D3 (1alpha,25(OH)(2)D3 or thapsigargin (Tpg)-induced depletion of Ca(2+) stores. In view of recent evidence favoring a role for transient receptor potential (TRP) proteins in mediating CCE, we investigated if(More)
As in other vitamin D target cells, activation of voltage-dependent Ca2+ channels (VDCC) mediates the fast, non-genomic, 1,25(OH)2D3 stimulation of Ca2+ influx in skeletal muscle cells (SMC). 1,25(OH)2D3 has also been shown to rapidly induce the release of Ins(1,4,5)P3 in SMC. Experiments were performed to investigate whether Ca2+ release-activated Ca2+(More)
We have previously reported that the calciotropic hormone 1,25(OH)2-vitamin D3 stimulates influx of Ca2+ into cultured rat and embryonic chick myoblasts via voltage sensitive Ca(2+)-channels. In the present study, we show that this effect of 1,25(OH)2D3 requires the mediation of the adenylylcyclase signalling system since the hormone-dependent Ca2+ influx(More)
Developmental changes in the protein, phospholipid, cholesterol, and fatty acid composition of skeletal and cardiac microsomes were correlated with CaZf transport activity in chicken embryos and during the early postnatal period. In skeletal muscle microsomes isolated from leg, superficial pectoralis, or deep pectoralis muscles, the rapid increase in the(More)
We previously reported that 1alpha,25(OH)2D3 induces non-transcriptional rapid responses through activation of MAPKs in C2C12 skeletal muscle cells. However, there is little information on the molecular mechanism underlying the initiation of 1alpha,25(OH)2D3 signaling through this pathway. Plasma membrane components have been involved in some non-genomic(More)
Recent studies have provided evidence for nuclear estrogen receptor-mediated calcium transport in intestinal mucosal cells. The possibility that, in addition, estrogens directly stimulate intestinal Ca2+ fluxes through second-messenger pathways was investigated. Exposure of enterocytes isolated from female rat duodenum to low physiological levels of 17(More)