title: Reduced RhoA activity mediates acute alcohol intoxication-induced inhibition of lymphatic myogenic constriction despite increased cytosolic [Ca(2+) ].
abstract: OBJECTIVE
  We previously showed that AAI reduces lymphatic myogenic constriction in response to step increases in luminal pressure. Because of the known role of Ca(2+) in smooth muscle contractile responses, we investigated how alcohol impacts cyclic Ca(2+) and whether changes in RhoA/ROCK-mediated Ca(2+) sensitivity underlie the alcohol-induced reduction of myogenic responsiveness.
  
  
  METHODS
  AAI was produced by intragastric administration of 30% alcohol in rats. Mesenteric lymphatics were cannulated and loaded with Fura-2 AM to [Ca(2+) ]i for 30 minutes after AAI. Active GTP-bound RhoA levels were determined by ELISA. To determine ROCK's ability to restore myogenic responsiveness following AAI, isolated lymphatics were transfected with constitutively active ca-ROCK protein.
  
  
  RESULTS
  Lymphatics from alcohol-treated rats displayed significantly larger Ca(2+) transients. Also, step increases in luminal pressure caused a gradual rise in the basal [Ca(2+) ]i between transients that was greater in lymphatics submitted to AAI, compared to vehicle control. RhoA-GTP was significantly reduced in lymphatics from the AAI group, compared to vehicle control. Transfection with ca-ROCK protein restored the myogenic response of lymphatic vessels isolated from AAI animals.
  
  
  CONCLUSIONS
  The data strongly suggest that the alcohol-induced inhibition of mesenteric lymphatic myogenic constriction is mediated by reduced RhoA/ROCK-mediated Ca(2+) sensitivity.
authors.affiliation: Department of Physiology, Alcohol and Drug Abuse Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA. fsouz1@lsuhsc.edu
authors.forename: Flavia M
authors.initials: FM
authors.lastname: Souza-Smith
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Molina
authors.forename: Jerome W
authors.initials: JW
authors.lastname: Breslin
mesh_terms: D000208:Acute Disease; D000435:Alcoholic Intoxication / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D042601:Lymphatic Vessels / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D002118:Calcium