We investigated the release of a stable contractile factor(s) from rabbit isolated polymorphonuclear leukocytes (PMNs; 108 cells/ml) incubated in Tyrode buffer at 37°C. PMNs were untreated, stimulated with N-formylmethionyl-leucyl-phenylalanine (FMLP; 0.1 μM), or degranulated with cytochalasin B (1 μM) in combination with FMLP (0.1 μM). Products from unstimulated PMNs incubated for 60 min cause...

Stretching of activated skeletal muscles induces a force increase above the isometric level persisting after stretch, known as residual force enhancement (RFE). RFE has been extensively studied; nevertheless, its mechanism remains debated. Unlike previous RFE studies, here the excess of force after stretch, termed static tension (ST), was investigated with fast stretches (amplitude: 3-4% sarcom...

The excitability of short segments (5-7 mm) of bundles of canine Purkinje fibers was depressed by exposure to 15-18 mM K(+), to 15-18 mM K(+) plus 5 x 10(-6) epinephrine or norepinephrine, to low K(+), and to low Na(+). The depressed segment was in the center chamber of a three-chamber bath; the ends of the bundle were exposed to normal Tyrode solution. Each method of depression resulted in slo...

In cardiac cells, evoked Ca2+ releases or spontaneous Ca2+ waves activate the inward Na+/Ca2+ exchange current (INaCa), which may modulate membrane excitability and arrhythmogenesis. In this study, we examined changes in membrane potential due to INaCa elicited by sarcoplasmic reticulum (SR) Ca2+ release in guinea pig ventricular myocytes using whole cell current clamp, fluorescence, and confoc...

MUSTARD,, J .FRASER,DENNIS W .YERRY, RAELENE L. KINLOUGHRATHBONE, AND MARIAN A. PACKHAM. Factors resfonsible for ADPinduced release reaction of human platelets. Am. J. Physiol, 228(6) : 17571765. 1975,-Extensive aggregation of human platelets can be induced by ADP without secondary aggregation or release of granule contents. This occurs with washed platelets in Tyrode solution containing 0.35 Y...

The ability of Mycoplasma pneumoniae cells and membranes to affect tetrazolium reduction by hamster trachea organ cultures was evaluated. Uninfected trachea explants reduced 2,3,5-triphenyl tetrazolium chloride (TTC) and nitro-blue tetrazolium when incubated at 37 C in the absence of air. Reduced tetrazolium salts (formazans) were extractable with acetone or ethylene glycol and could be quantit...

Small trabeculae of rabbit left atrium immersed in TKBa solution (Tyrode with 10 mM K+ and 1 mM Ba2+) were used to study frequency dependence of "membrane" slow response excitability at long cycle lengths (>1 s) . In TKBa, stimuli generate graded, low-amplitude (2-15 mV) subliminal responses of variable long duration (up to 450 ms) . A full all-or-none slow response is generated when a sublimin...

WOOD, J. D. Excitation of intestinal muscle by atropine, tetrodotoxin, and Xylocaine. Am. J. Physiol. 222(l): li8-125. 1972.-The circular muscle layer of cat jejunum was mechanically and electrically quiescent when equilibrated in Tyrode solution at 37 C. Atropine, procaine, tetrodotoxin, and Xylocaine produced action potentials and a large increase in the amplitude of contractions in the circu...

the aim of this study was to investigate the effect of aerial parts of stachys lavandulifolia vahl. extract on the rat ileum contractions. the crude extract was prepared by maceration method (90% methanol) followed by fractionating into chloroform, ethyl acetate, petroleum ether and water. in adult male wistar rats, ileum was sectioned and mounted in tissue bath and their contractility was reco...

This study was directed to the ability of oxygen free radicals to cause reversible vascular endothelial cell dysfunction. A well-characterized system for the production of the superoxide anion radical (O2(-).) and hydrogen peroxide (H2O2), employing xanthine and xanthine oxidase, was used to sublethally injure human umbilical vein endothelial (HUVE) cells in vitro. We examined the effects of a ...