Increased concentration of leukotriene B4 but not thromboxane B2 in intestinal lymph of cats during brief ischemia

Abstract

Mesenteric ischemia stimulates both A delta- and C-fiber afferents to reflexly activate the cardiovascular system. Leukotriene B4 (LTB4) concentration is increased in intestinal mucosa following prolonged ischemia (3 h) followed by reperfusion. Because LTB4 sensitizes afferent nerve endings in the skin, we determined whether LTB4 is produced during brief mesenteric ischemia and thus would be present to sensitize afferent nerve endings in the abdominal visceral region. Cannulas were placed in the portal vein and in a mesenteric lymphatic vessel distal to the lymph node. Mesenteric lymph and portal venous immunoreactive LTB4 (iLTB4) and immunoreactive thromboxane B2 (iTxB2) concentrations were measured before, during, and after 5-7 min of ischemia induced by occlusion of the descending thoracic aorta in cats. Simultaneously, lymph and plasma lactate concentrations were measured. During arterial occlusion, femoral arterial pressure dropped to less than 30 mmHg, and portal venous and mesenteric lymph lactate concentrations were increased significantly (3.3 +/- 0.6 to 6.3 +/- 1.0 mM and 5.2 +/- 0.9 to 7.2 +/- 1.1 mM, respectively, P less than 0.05). During ischemia, iLTB4 concentration increased in lymph from 261 +/- 70 to 424 +/- 102 pg/0.1 ml (P less than 0.05) but did not increase in portal venous blood (135 +/- 26 vs. 168 +/- 44 pg/0.1 ml, control vs. ischemia). iTxB2 concentration was not increased during ischemia in either portal venous blood or lymph (12 +/- 4 to 24 +/- 9 pg/0.1 ml and 19 +/- 7 to 24 +/- 11 pg/0.1 ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)