NO- and prostanoid-independent relaxations are generally assumed to be mediated by an endothelium-derived hyperpolarizing factor (EDHF) that has been postulated to be an arachidonic acid metabolite. Recent evidence also suggests that direct heterocellular gap junctional communication (GJC) between endothelium and smooth muscle contributes to NO-independent relaxations. In the present study we h...

BACKGROUND AND PURPOSE Experiments were designed to determine the effect of subarachnoid hemorrhage on endothelium-dependent relaxations in small arteries of the brain stem. A "double-hemorrhage" canine model of the disease was used, and the presence of vasospasm in the basilar artery was confirmed by angiography. METHODS Secondary branches of both untreated basilar arteries (inner diameter, ...

We have isolated and characterized a 12-kb mouse genomic DNA fragment containing the entire calreticulin gene and 2.14 kb of the promoter region. The mouse calreticulin gene consists of nine exons and eight introns, and it spans 4.2 kb of genomic DNA. A 1.8-kb fragment of the calreticulin promoter was subcloned into a reporter gene plasmid containing chloramphenicol acetyltransferase. This cons...

Human recombinant histamine-releasing factor (HrHRF) preincubation enhances the secretion of histamine, IL-4, and IL-13 from FcepsilonRI-stimulated human basophils. In GM-CSF-primed human eosinophils, HrHRF increases IL-8 production. Our recent experiments were designed to evaluate the effects of HrHRF on human T cell cytokine production. Purified T cells were preincubated with GST-tagged HrHRF...

A small quantity of extracellular calcium is required for the stimulation of lymphocytes by mitogens such as plant lectins. Lectin binding to the lymphocyte surface and early postbinding events that eventually lead to DNA synthesis are calcium dependent. Mitogenic lectins such as PHA and Con-A rapidly increase the size of an exchangeable pool of cell calcium and cause a smaller rise in intracel...

Phosphatidylserine exposure and microvesicle release give rise to procoagulant activity during platelet activation. We have previously shown that whereas the Ca2+ ionophore A23187 and 2,5-di-(t-butyl)-1, 4-benzohydroquinone, a Ca2+-ATPase inhibitor, induce phosphatidylserine exposure, only the former triggers microvesicle release. We now report that microvesicle formation with ionophore A23187 ...

Increasing free intracellular Ca (Cai) from less than 0.1 microM to 10 microM by means of A23187 activated Ca-stimulated K transport and inhibited the Na-K pump in resealed human red cell ghosts. These ghosts contained 2 mM ATP, which was maintained by a regenerating system, and arsenazo III to measure Cai. Ca-stimulated K transport was activated 50% at 2-3 microM free Cai and the Na-K pump was...

Bovine epididymal spermatozoa incubated aerobically in vitro in the presence of 0.1 to 0.2 mM CaCl2 accumulate 25 to 50 nmol of calcium/10(8) cells. The addition of low concentrations of the ionophore A23187 (0.01 to 0.5 nmol/mg of sperm protein) induces efflux of this accumulated calcium. At high ionophore concentrations (0.5 to 5.0 nmol/mg of sperm protein), calcium release is followed by an ...

BACKGROUND/AIMS In previous publications we were able to demonstrate the exposure of phosphatidylserine (PS) in the outer membrane leaflet after activation of red blood cells (RBCs) by lysophosphatidic acid (LPA), phorbol-12 myristate-13acetate (PMA), or 4-bromo-A23187 (A23187). It has been concluded that three different mechanisms are responsible for the PS exposure in human RBCs: (i) Ca2+-sti...