phalloidine and Edema

Lowering of interstitial fluid pressure (Pif) facilitates fluid filtration across the capillary membrane and oedema formation in acute inflammation. The cellular mechanism behind this lowering of Pif involves beta1-integrins mediating contact between dermal cells and the extracellular matrix fibres, and also the cell cytoskeleton as disruption of actin filaments using cytochalasin-D induced a lowering of Pif and oedema formation. Fixation of actin with phalloidin attenuates oedema formation and abolishes lowering of Pif in anaphylaxis in the rat. The objective of this study was to determine whether phalloidin modifies lowering of Pif and albumin extravasation in rat skin also after prostaglandin E1 (PGE1).. Pif was measured using micropipettes connected to a servo-controlled counterpressure system. Microvascular permeability was estimated as the albumin extravasation (Ealb) using radiolabelled human serum albumin.. Subdermal injection of PGE1 (0.85 mg mL-1) lowered Pif from -0.8 +/- 0.8 mmHg (SD) in control to -3.5 +/- 0.9 mmHg (P < 0.05) within 30 min. Pre-treatment with phalloidin (500 microg kg-1) before PGE1 resulted in Pif of -1.7 +/- 1.0 mmHg (P < 0.05 compared with PGE1). Ealb after subdermal saline was 0.07 +/- 0.04 mL g-1 DW and increased to 0.32 +/- 0.32 mL g-1 DW with PGE1 (P < 0.05) but was unaffected by pre-treatment with phalloidin given before PGE1 0.32 +/- 0.35 mL g-1 DW (P > 0.05 compared with PGE1 alone).. These results are consistent with the concept that the cytoskeleton actin filaments participate in control of Pif.

Topics: Albumins; Alprostadil; Animals; Biological Transport; Connective Tissue; Cytoskeleton; Edema; Extracellular Fluid; Female; Fixatives; Infusions, Intravenous; Phalloidine; Pressure; Rats; Rats, Wistar; Skin

The purpose of this study was to examine the relationship of increased capillary network resistance due to leukocyte-capillary plugging and tissue edema through macromolecular leakage to tissue injury after ischemia-reperfusion (I/R). After a 3-h complete ischemia in the dorsal skinfold chamber of the awake Syrian hamster, the following parameters were measured: vessel diameter, macromolecular leakage, erythrocyte velocity, adherent leukocytes, rolling leukocytes, freely flowing leukocytes, functional capillary density (FCD), propidium iodide (PI)-positive cell nuclei, and increase in network flow resistance due to leukocyte-capillary plugging. These measurements were made under baseline conditions and after 0.5 and 2 h of reperfusion for I/R alone, I/R with phalloidin (PL) treatment (to block leakage), and I/R with both PL and cytochalasin D (CD) (to block both leakage and plugging). Neither treatment had an effect on the leukocyte adherence or rolling. PL treatment preserved the endothelial barrier, improved FCD, and reduced the amount of PI measured tissue damage. CD treatment eliminated the increase in network resistance due to leukocyte plugging but did not improve FCD or tissue damage. Thus, in this I/R model, macromolecular leakage plays a role in tissue injury, whereas leukocyte plugging does not appear to be an important mechanism.

Topics: Animals; Capillaries; Capillary Permeability; Cell Adhesion; Cricetinae; Cytochalasin D; Edema; Ischemia; Leukocytes; Macromolecular Substances; Male; Mesocricetus; Muscle, Skeletal; Phalloidine; Reperfusion Injury

The aim of this study was to determine whether the formation of edema that occurs secondary to the neutrophil-dependent increase in microvascular permeability contributes to the genesis of no-reflow in postischemic skeletal muscle. To address this issue, four experimental approaches were used. In the first group, capillary perfusion was assessed in nonischemic canine gracilis muscles in which interstitial fluid volume was increased to a level similar to that in postischemic muscle. In the second and third groups, edema formation was prevented in postischemic skeletal muscles by administration of phalloidin or a hypertonic hyperosmotic saline-dextran solution (HSD; 7.5% saline-6% Dextran 70), and the extent of capillary no-reflow was assessed. In the final group of experiments, a monoclonal antibody (MAb) that binds to the common beta-subunit of the leukocyte integrin CD11/CD18 (MAb IB4) was administered after the development of postischemic edema, and capillary perfusion was determined. Formation of edema in nonischemic preparations and ischemia-reperfusion (I-R) were associated with marked reduction in the number of patent capillaries per fiber (1.2 +/- 0.1 and 0.4 +/- 0.1, respectively) compared with nonedematous nonischemic controls (2.5 +/- 0.3). Treatment with phalloidin or HSD prevented edema formation and attenuated the reduction in the number of patent capillaries per fiber (1.62 +/- 0.2 and 1.71 +/- 0.2, respectively) induced by I-R, whereas administration of MAb IB4 after the formation of edema in reperfused muscles failed to limit capillary no-reflow (0.5 +/- 0.1 patent capillaries/fiber).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Analysis of Variance; Animals; Capillaries; Cell Adhesion; Dogs; Edema; Female; Hindlimb; Hypertonic Solutions; Ischemia; Leukocytes; Male; Mice; Muscle, Smooth, Vascular; Muscles; Neutrophils; Phalloidine; Reference Values; Regional Blood Flow

Interleukin 2 (IL-2) is a potent cytokine with diverse effects, including the ability to stimulate lymphocyte differentiation into cells capable of lysing tumor. Its therapeutic efficacy is limited because of side effects such as breakdown of the microvascular barrier and edema. Control of the microvascular barrier is in part regulated by endothelial cell cytoskeletal contractile proteins. This study tests whether the cyclopeptides that maintain actin filament organization and distribution and reduce macromolecular flux across the endothelial cell junction in vitro would similarly maintain barrier tightness and prevent early edema produced by IL-2 in vivo. Anesthetized rats were treated at 30-min periods with intravenous saline (0.5 ml, n = 41), phalloidin (20 micrograms in 0.5 ml, n = 21), or antamanide, (20 micrograms in 0.5 ml, n = 21), starting 30 min before the 1-h infusion of 10(6) U of recombinant human IL-2 or saline. Six hours after the start of IL-2, there was edema in the saline/IL-2 group, as measured by increased wet-to-dry ratios (W/D) in the lungs, heart, and kidney. With saline/IL-2, bronchoalveolar lavage (BAL) fluid contained an elevated protein concentration and higher plasma thromboxane levels compared with controls. The number of neutrophils sequestered in the lungs was more than twice that of saline controls. Phalloidin significantly attenuated edema in lung and reduced BAL protein leak. Antamanide treatment was as effective in limiting lung and heart edema, but, in contrast to phalloidin, antamanide prevented kidney edema and did not lead to an alteration in the liver W/D. Antamanide also prevented BAL fluid protein leak.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Capillary Permeability; Chemical and Drug Induced Liver Injury; Edema; Edema, Cardiac; Interleukin-2; Kidney Diseases; Liver Diseases; Male; Peptides, Cyclic; Phalloidine; Pulmonary Edema; Rats; Rats, Inbred Strains; Thromboxane B2

The K+ release from the isolated perfused rat liver induced by phalloidin was strongly inhibited on raising the Mg2+ concentration of the perfusion medium from 0.5-40mM while, in contrast, the phalloidin induced swelling of the organ and the vasuolisation of the liver tissue was not affected.

Topics: Animals; Biological Transport; Chemical and Drug Induced Liver Injury; Edema; In Vitro Techniques; Liver; Magnesium; Male; Oligopeptides; Organ Size; Phalloidine; Potassium; Rats