Changes In Mesenteric Flow Research Articles

Flujo mesentérico en un modelo experimental por isquemia-reperfusión en ratas

IntroductionMaintained acute occlusion followed by reperfusion of the superior mesenteric artery (SMA) in a few hours can trigger irreversible bowel damage. The aim of the study was to determine the changes in mesenteric flow measured by colour Doppler Ultrasound and correlating with histological lesions in an experimental model of ischaemia-reperfusion. Method and materialThree groups of Sprague-Dawley 17 day-old rats were studied (control, ischemia and reperfusion). The model used was ischaemia-reperfusion over the SMA. Intra-abdominal ultrasound was then performed. The parameters recorded were: Maximum systolic velocity (MSV), pulsatility index (PI), resistance (RI) and systole-diastole (S/D). The histological variables were: intestinal lesion (Wallace/Keenan-Chiu scale), morphometrics (mean villus height [MVH]), and goblet cells. The Spearman (rs) correlation was used. ResultsThe MSV in the reperfusion group was 74.3cm/s, the PI 7.33 and S/D 25.75 in the SMA, which were higher than the controls (41.35cm/s; 3.12 and 12.45, respectively). A direct association (P<.01) was found between MSV, PI and S/D regarding: Wallace/Kennan scoring system (rs = 0.655; rs = 0.593; rs = 0.63) and the Chiu (rs = 0.569; rs = 0.522; rs = 0.47). While the correlation was the reverse (P<.01) when associated with the MVH (rs = –0,495; rs = –0,452; rs = –0,459) and goblet cells of the colon (rs = –0,525; rs = –0,45; rs = –0,518). ConclusionsThe reperfusion phase increased mesenteric flow expressed by the MSV and PI and could significantly predict the potential bowel damage at macroscopic and microscopic level.

The effect of distension of the stomach on peripheral blood flow in anaesthetized pigs.

The present study was undertaken in anaesthetized pigs to determine the primary reflex effects of gastric distension on the peripheral circulation. Changes in blood flow in the splenic, superior mesenteric, left renal and left external iliac arteries were assessed using electromagnetic flowmeters during distension of a balloon in the stomach, performed at constant aortic blood pressure and heart rate, with 0.6 l of Ringer solution (mean gastric transmural pressure of about 12 mmHg). In fourteen pigs, a decrease in splenic, renal and iliac flows and variable changes in mesenteric flow were obtained. A decrease in mesenteric flow and more marked decreases in the other flows occurred in response to the distension after the administration of propranolol or butoxamine. In five pigs, the vasoconstrictive responses were graded by step increments in gastric distending volume from 0.4 to 0.8 l. The above responses were abolished by the administration of phentolamine (eight pigs) and by bilateral cervical vagotomy (six pigs). The results showed that innocuous distension of the stomach in anaesthetized pigs reflexly caused vasoconstriction in the splenic, renal and iliac vascular beds; vasoconstriction also occurred in the mesenteric vascular bed but only after beta-blockade. These reflex responses were mediated by sympathetic mechanisms which involved both alpha and beta vascular adrenoceptors and their afferent limb was in the vagal nerves.

Circulatory effects of intraduodenal acidification in the rat.

The effect of intraduodenal administration of 0.3 ml/100 g 0.1 N hydrochloric acid and of the i.v. injection of 0.3 U/100 g secretin on the regional circulation was investigated in rats with the radioactive microsphere method. Intraduodenal acid produced a threefold increase in duodenal blood flow, jejunal perfusion was doubled, the perfusion of pancreas increased significantly. There were no significant changes in cardiac output, renal, myocardial, gastric and ileal blood flow. Secretin administration was without effect on the circulation. The same hormone dose produced a tenfold increase in pancreas secretion but was without effect on bile output. It is concluded that in the rat low doses of secretion do not elicit mesenteric flow changes similar to those observed after duodenal acidification.