The effect of the extracellular Ca depletion on potassium contracture was investigated in single fibers isolated from frog semitendinosus muscle mainly in relation to its time and Na dependency. The shortening of plateau duration and the increase in the rate of relaxation of the potassium contracture appeared within 3--5 sec and 15 sec, respectively, after the fiber was immersed in Ca-free Na R...

The structure andextinctionbehaviorofpartiallypremixed  ames ina counter owconŽ gurationare investigated by using Ž ve different chemistry models. These include the C1 and C2 mechanisms of Peters and Rogg (Peters, N., and Rogg, B., Reduced Kinetic Mechanisms for Applications in Combustion Systems, Springer–Verlag, Berlin, 1993, pp. 8–12), a 12-step augmented reduced mechanism, andGRI-2.11 and...

The calcium sequestering agent, EGTA, was injected into Limulus ventral photoreceptors. Before injection, the inward membrane current induced by a long stimulus had a large initial transient which declined to a smaller plateau. Iontophoretic injection of EGTA tended to prevent the decline from transient to plateau. Before injection the plateau response was a nonlinear function of light intensi...

Literature values for the Kd for Ca2 + in bovine a-lactalbumin range over 3 orders of magnitude. There is a difference between two results obtained with EGTA as a metalion buffer, partly because different values for the Kd of Ca2 +-EGTA were used in the calculations, and a much wider difference between results obtained in the presence and absence of EGTA, which has been attributed to an interac...

The infusion of thyrocalcitonin (TCT) into thyroparathyroidectomized rats, given either no exogenous parathyroid hormone or a constant infusion of this hormone, leads to a transient phosphaturia and a decreased excretion of urinary magnesium, calcium, and hydroxyproline without a change in glomerular filtration rate. The changes in phosphate excretion may be due to a direct effect of the hormon...

In many experimental biological situations, chelating agents like EGTA (ethylene glycol-bis-(beta-amino-ethyl ether) N,N,N',N'-tetra-acetic acid) are commonly used to control or suppress the concentration of divalent ions like Ca2+. The evaluation of liquid junction potentials in electrophysiological measurements, and particularly in patch-clamp situations, requires information about the ions w...

The ability of fowl spermatozoa to accumulate and de-esterify the intracellular fluorescent Ca2+ indicator fura-2 was established. The cytosolic Ca2+ concentrations, measured by this technique, did not change after the addition of 1 mmol EGTA l-1. Subsequently, addition of the calcium ionophore A23187 caused a reduction in cytosolic Ca2+ concentrations, presumably by efflux of Ca2+ from the spe...

Caged-Ca(2+) compounds such as nitrophenyl-EGTA (NP-EGTA) and DM-nitrophen (DMn) are extremely useful in biological research, but their use in live cells is hampered by cytoplasmic [Mg(2+)]. We determined the properties of Ca(2+) release from NP-EGTA and DMn by using Oregon green BAPTA-5N to measure changes in [Ca(2+)] after ultraviolet flash photolysis in vitro, with or without Mg(2+) present....