Inflammation
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Membrane depolarization is an early event in cell stimulation. Since the resting membrane potential is dependent on the potassium composition of the extracellular medium, we investigated whether there are clinical situations in which potassium levels are high enough to depolarize polymorphonuclear leukocytes. We determined the ionic composition of sterile and infected interstitial fluid in humans and guinea pigs. ⋯ In contrast, human abscess fluids contained increased K+-levels (17 +/- 6.4 mmol/liter, N = 8) and 15 of 20 experimental abscesses in guinea pigs contained greater than 10 mmol/liter K+. In humans three of eight abscess fluid K+ levels and in guinea pigs three of five abscess fluid K+ levels were even greater than 15 mmol/liter. Thus, high K+ levels, previously shown to activate polymorphonuclear leukocytes, are observed in certain clinical situations associated with local inflammation.
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Comparative Study
In vivo and in vitro effects of dexamethasone on leukocyte migration in the rat adjuvant arthritis model.
When polymorphonuclear leukocytes (PMNs) and mononuclear cells were isolated from the blood of dexamethasone-treated normal rats, in vitro mononuclear cell migration was inhibited and PMN migration was stimulated in comparison to controls. Inflammogen-induced PMNs showed inhibited cell migration due to dexamethasone treatment. ⋯ When the dexamethasone-treated blood cells were injected into adjuvant arthritis diseased rats, mononuclear cells showed depressed migration into the inflamed paws, while PMNs showed stimulated migration into the inflamed paws in comparison to controls. When the recipient adjuvant arthritic animals were treated with dexamethasone, both normal mononuclear cell and normal PMN migration to the inflamed paws were inhibited.