Role of Rho kinase and actin filament in the increased vascular permeability of skin venules in rats after scalding.
OBJECTIVE
To investigate the role of the Small GTPase Rho and endothelial cytoskeleton in the increased vascular permeability of rat skin after scalding.


METHODS
Rats were subjected to scalding local ventral skin and a venule was isolated from scalded skin and cannulated by micropipette. The venular permeability was measured with a fluorescence ratio technique and expressed with the permeability coefficient to albumin (P(a)). The venular F-actin filaments were observed by staining with rhodamine phalloidin and laser confocal scanning microscopy. A specific Rho kinase inhibitor Y-27632 was added into vessel bathing solution or preincubated with vessels to evaluate the role of Rho kinase in regulating of vascular barrier function.


RESULTS
Scalding increased P(a) value of skin venule about threefold compared to normal skin venules (P<0.01) and was maintained for 120 min. Inhibition of Rho kinase with Y-27632 (30 micromol/l in low-concentration group; 60 micromol/l in high-concentration group) significantly attenuated the hyperpermeability responses to scalding in a dose dependent fashion. A prominent peripheral actin rim (PAR) existed at the outer area of endothelial cells and apparently delineated the cell-to-cell borders. In the control group, the PARs were arranged smoothly and fairly continuously. However, occasionally PARs did show focal interruption with focal fluorescein isothiocyanate (FITC)-albumin leakage. In the burned group, PARs were less organized and accompanied by a large amount of FITC-albumin leakage. Inhibition of Rho kinase with Y-27632 dramatically reduced P(a) value with recovery of actin filament arrangement in venule after scalding.


CONCLUSIONS
Burn leads to dermal venular permeability increase with endothelial cytoskeleton depolymerization and disruption. Rho signal transduction pathway is involved in these responses.
Zheng
Hui-zhen
HZ
PLA Key Laboratory for Shock and Microcirculation, First Military Medical University, 510515, Guangzhou, China.
Zhao
Ke-seng
KS
Zhou
Bi-ying
BY
Huang
Qiao-bing
QB
D000199:Actins / Q000378:metabolism*; D000577:Amides / Q000494:pharmacology; D000818:Animals; D002056:Burns / Q000378:metabolism / Q000473:pathology*; D002199:Capillary Permeability / Q000187:drug effects; D003599:Cytoskeleton / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D018613:Microscopy, Confocal; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000098:blood supply*; D014699:Venules / Q000502:physiology; D054460:rho-Associated Kinases
D000199:Actins; D000577:Amides; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D011725:Pyridines; C108830:Y 27632; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases