Francine B. Orner

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We studied the cAMP response of cultured rat calvaria to parathyroid hormone (PTH) and prostaglandins (PG) in order to test the hypothesis that PTH action is mediated by PG. PTH and PGE1 each caused an 8-fold increase in tissue cAMP during 15 min incubation. There was an additive response to the combination of the two agonists at maximally effective(More)
Cord basophil preparations from 53 term neonates were studied for various factors affecting immediate hypersensitivity reactions including: basophil IgE receptor density and histamine releasability following incubation with calcium ionophore A23187, zymosan-activated serum (C5a), and anti-IgE. Basophil histamine content (geometric mean, 0.4 pg/basophil,(More)
Rat peritoneal mast cells were desensitized up to 100% with 1-4 additions of suboptimal concentrations of anti-rat IgE over 60-90 min. Desensitized cells rechallenged with anti-IgE showed a 2- to 10-fold increase in cAMP during the initial 1-5 min. Membrane preparations from desensitized cells showed up to a 100-fold rise in cyclase activity following(More)
Cells digested from adult rat heart and cultured for 14 days demonstrate all the structural elements, in mature form, associated with the process of excitation-contraction (EC) coupling. The transverase tubular (TT) system is well developed with an extensive junctional sarcoplasmic reticulum (JSR). In nonphosphate-containing buffer contraction of the cells(More)
We evaluated the hypothesis that thiazide-induced hypercalcemia reflects potentiation of the cAMP response to parathyroid hormone (PTH) consequent to inhibition of phosphodiesterase in bone and kidney. A panel of thiazide diuretics did inhibit low-Km phosphodiesterase activity from bone homogenates. However, furosemide, a nonthiazide diuretic that does not(More)
We used an in vivo infusion technique to assess the hypothesis that vitamin D metabolites and estrogens modulate tissue responsiveness to parathyroid hormone via effects on the adenylate cyclase-cAMP system. After treatment with these agents for 3-4 days, rats were thyroparathyroidectomized. Twenty-four hours later, parathyroid extract (PTE) was infused,(More)
Parathyroid Hormone (PTH) stimulates calcium entry into bone cells in vitro, and this effect has been proposed to mediate the actions of PTH on bone. Using cells harvested from infant rat calvaria by collagenase digestion, we evaluated the sensitivity and specificity of this phenomenon. Calcium uptake was temperture dependent, and was increased by PTH over(More)
Desensitization in normal rat peritoneal mast cells was induced by subthreshold and suboptimal levels of antirat IgE under normal calcium buffer conditions. Low doses of anti-IgE which triggered 0-10% net histamine release, initiated up to 100% desensitization. The rate of desensitization was highly variable in different rats, resulting in an irregular(More)
Freshly prepared ventricular myocytes from rat hearts, aliquots of which were tested for sarcolemmal integrity by La exposure, were labeled at high 45Ca specific activity. Isotope was subsequently washed out at a perfusion rate of 2.8 ml/s with washout solution sampled each 1 s. No initial unrecorded period of washout was imposed. Four compartments were(More)
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