Effect of phalloidin on structure and permeability of rete capillaries in the normal and hypoxic state.

Abstract

The effects of 10(-6) M phalloidin on reperfusion-injured blood capillary structure and permeability were studied in the countercurrent perfused rete mirabile of the eel swim bladder. In the normal rete, the addition of phalloidin to the perfusion medium did not induce morphological or functional changes. When flow was arrested for 30 minutes, during which time the capillaries were exposed to inhibitors of ATP generation, and flow was then resumed with an oxygenated medium, cell membrane blebs and vacuolization, mitochondrial swelling, pericyte shrinkage, and interstitial space edema were observed. The permeability coefficients for labeled albumin, sucrose, and sodium increased to three to four times baseline values, whereas the permeability to water was not significantly modified. When the same protocol was repeated with phalloidin present in the medium throughout the experiment, the structural integrity of the endothelial cells was completely preserved and pericyte shrinkage was abolished, but interstitial space edema still occurred. The permeability to albumin, sucrose, and sodium increased only to 1.5 times baseline values, a significantly decreased increment in comparison with the experiments performed without phalloidin. We concluded that although phalloidin does not improve the capillary barrier of the normal rete, it provides protection against the structural and functional damage induced by hypoxia and reperfusion.

Thrombin-Induced Alterations in Endothelial Cell Cytoarchitectural and Functional Properties

“…The authors suggested that 5-HT helped to regulate endothelial junc tional stability by promoting actin filament formation and stability, as had been demonstrated by Montesano et al 25 for the phalloidin-mediated induction of tight junctional elements. Rasio et al 26 demonstrated that phalloidin pretreatment provided protection against structural and func tional damage induced by hyperoxia-reperfusion in rete capillaries.…”

Changes in the Actin Cytoskeleton of Cardiac Capillary Endothelial Cells during Ischaemia and Reperfusion: The Effect of Phalloidin on Cell Shape

“…Active capillary constriction has been demonstrated in rete capillaries, in the spleen and in the pancreas to occur to such an extent that red blood cell flow was impeded [1, 2, 3]. Similar observations have not, however, been made in the cardiac microvasculature, possibly as a result of the inaccessibility of the capillary bed to in vivo observation.…”

Early and delayed tolerance to simulated ischemia in heat-preconditioned endothelial cells: a role for HSP27

“…INTEGRITY of the filamentous (F)-actin structures in the vascular endothelium is necessary for its physiological functioning as a selectively permeable barrier (30,32,33,40). Increased permeability of the endothelial barrier provokes edema that can result in severe injury of the adjacent tissue.…”