RELEASE OF ENDOTHELIN-1 IN STRANGULATION OBSTRUCTION OF THE SMALL-BOWEL IN PIGS

Evidence has been provided that increased portal vein pressure results in increased release of endothelin-l (ET-1). Strangulation obstructio n is associated with increased venous pressure, and we wanted to deter mine if it is associated with increased local release of ET-1 and elev ated concentration of ET-1 in systemic blood. Strangulation obstructio n was induced by elevating pressure in a gasket placed around a loop o f ileum until venous pressure reached 50 mm Hg. Ischemia in a bowel lo op was induced by arterial clamping, reducing blood flow by 70%. Blood samples were collected before and after 30, 90, and 180 min of strang ulation or ischemia, ET-1 was determined by radioimmunoassay following acidification and extraction on C-18 columns. In strangulated loop th e blood flow decreased by 70%. ET-1 concentration remained around 5 pg /ml in arterial blood, increased fourfold in strangulated venous blood , and remained unchanged in venous blood from control bowel. The relea se of ET-1 from the strangulated loop to blood increased twofold. Isch emia resulted in reduced release of ET-1, It is concluded that strangu lation obstruction causes increased release of ET-1 to venous blood in the strangulated loop, but not increased ET-1 concentration in system ic blood, The increased ET-1 release was probably due to increased ven ous pressure, not to low blood how. (C) 1998 Academic Press.