Concentrations of the divalent cation ionophore, A23187, optimal for the transformation of human and pig lymphocytes, were cytotoxic to lymphocytes from rats and mice. The biochemical effects associated with A23187-induced cytolysis in rat thymocytes included inhibition of [3H]uridine uptake and incorporation into macromolecules and stimulation of [14C]-alpha-aminoisobutyric acid uptake. The bi...

BACKGROUND Before a spermatozoon can fertilize an oocyte it must undergo a cascade of biochemical and physiological changes that facilitate its binding and penetration into the oocyte. Epididymal protease inhibitor (eppin) has been found to play a critical role in male fertility through an immunological approach. METHODS In this study, we used an anti-eppin antibody to clarify the effect of e...

BACKGROUND In a variety of disease states, endothelium-dependent vasodilation is abnormal. Reduced nitric oxide (NO) production, increased destruction of NO by superoxide, diminished cellular levels of L-arginine or tetrahydrobiopterin, and alterations in membrane signaling have been implicated. We examined these potential mechanisms in human vessels. METHODS AND RESULTS Relaxations to acetyl...

Murine erythroleukemia (MEL) cells are a useful model for studying the processes that regulate erythroid differentiation because exposure of these cells to a variety of chemical inducing agents results in expression of erythroid-specific genes and the resultant loss of cellular immortality. Previously it has been suggested that the calcium ionophore, A23187, has effects on the early cellular ev...

In mouse-human heterokaryons, the lateral diffusion of major histocompatibility (MHC) antigens in the plasma membrane is enhanced by treatment of parent cells with ouabain. Ouabain treatment is ineffective if the medium lacks calcium ion, or if Verapamil, a blocker of calcium channels, is present. The divalent ionophore A23187 also enhances lateral diffusion of MHC antigens, to the same extent ...

The role of calcium in the pathogenesis of hypertrophic cardiomyopathy was investigated experimentally. For this purpose the calcium antagonist verapamil and the calcium ionophore A23187 were administered to pregnant rats together with triac in order to observe their effect on triac induced myocardial disarray and hypertrophy in developing rat hearts. At a low dose verapamil reduced both the le...

This study was designed to examine whether endothelin is released from the intima of intact arteries, and whether endothelium-derived nitric oxide regulates its production. Endothelin was detected in the incubating medium of unstimulated pig aortae with, but not in those without endothelium. In preparations with endothelium, thrombin (2-6 U/ml) and the calcium ionophore A23187 (10' M) stimulate...

To compare the mediator releasability between atopic and nonatopic asthmatics, we measured basophil histamine releasability (BaHR) using a calcium-ionophore A23187 and anti-IgE in 137 subjects who were treated at Seoul National University Hospital. Subjects were categorized into atopic (group AA, n=77) or nonatopic asthmatics (group NA, n=32), or normal controls (group NC, n=28). Serum total Ig...

Arachidonic acid (AA) released from membrane phospholipids by phospholipase A2 (PLA2) is important as a substrate for eicosanoid formation and as a second messenger for superoxide anion (O2-) generation in neutrophils. Different isoforms of PLA2 in neutrophils might mobilize AA for different functions. To test this possibility, we sought to characterize the PLA2s that are activated by the neutr...

Human peripheral blood leukocytes (PMN) are induced to release lysosomal enzymes by the calcium ionophore A23187 in the presence but not the absence of extracellular Ca++. Whereas secretion induced by particulate or immune stimuli is accompanied by an increase in visible microtubules and is inhibitable by colchicine, secretion induced by A23187 and Ca++ was not accompanied by an increase in mic...