The Ca2+-sensitive photoprotein aequorin (Mr = 20,000) was introduced into human blood platelets by incubation with 10 mM EGTA and 5 mM ATP. Platelet cytoplasmic and granule contents were retained during the loading procedure, and platelet morphology, aggregation, and secretion in response to agonists were normal after aequorin loading. Luminescence indicated an apparent resting cytoplasmic ion...

We proposed earlier that voltage-dependent calcium (Ca2+) current is altered in single azygos venous cells from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). In this study, the effects of different intracellular concentrations of ethylene glycol-bis-N,N,N',N',-tetraacetic acid (EGTA) on Ca2+ currents were investigated. Vascular muscle cells from SHR and WKY rats were equili...

Chromaffin granules, the catecholaminergic storage granules from adrenal chromaffin cells, lysed in 10(-9)-10(-7) M Fe2+. Lysis was accompanied by the production of malondialdehyde which results from lipid peroxidation. Both chromaffin granule lysis and malondialdehyde production were inhibited by the free radical trapping agent butylated hydroxytoluene but not by catalase and/or superoxide dis...

Isometric force and 45Ca loss from fiber to bath were measured simultaneously in skinned fibers from frog muscle at 19 degrees C. In unstimulated fibers, 45Ca efflux from the sarcoplasmic reticulum (SR) was very slow, with little or no dependence on EGTA (0.1-5 mM) or Mg++ (20 micrometer-1.3 mM). Stimulation by high [Cl] at 0.11 mM Mg++ caused rapid force transients (duration approximately 10 s...

We examined the progressive and irreversible loss of antigen-specific lymphoproliferative responses in peripheral blood mononuclear cells (PBMC) obtained from blood exposed for prolonged periods to EDTA as an anticoagulant. The responses of these lymphocytes to interleukin-2 or to concanavalin A were, however, unaffected. The observed loss was not due to depletion of metal ions by EDTA, since t...

Topical administration of sodium citrate reduces the incidence of corneal ulceration and perforation following an alkali burn to the eye. The specific mechanism by which sodium citrate prevents the ulceration is not understood, although citrate does inhibit the infiltration of polymorphonuclear leukocytes (PMNs) into the cornea following an alkali burn. In the present study, the effects of sodi...

Sea urchin spermatozoa demembranated with Triton X-100 in the presence of EGTA, termed potentially asymmetric, generate asymmetric bending waves in reactivation solutions containing EGTA. After they are converted to the potentially symmetric condition by extraction with Triton and millimolar Ca++, they generate symmetric bending waves in reactivation solutions containing EGTA. In the presence o...

Under optimal freeze-drying conditions, solutions exhibit a cake-like porous structure. However, if the solution temperature is higher than the glass transition temperature of the maximally freeze-concentrated phase (Tg') during drying phase, the glassy matrix undergoes viscous flow, resulting in cake collapse. The purpose of the present study was to investigate the effect of cake collapse on t...