Effect of triglycerides with different fatty acid chain length on superior mesenteric artery blood flow

Fat stimulates superior mesenteric artery (SMA) blood flow. Little is known, however, about the influence of fatty acid chain length on SMA flow. The present study was performed to compare the effect of long chain triglycerides (LCT, corn oil), very long chain triglycerides (VLCT, fish oil) and medium chain triglycerides (MCT) on SMA flow. A total of seven healthy volunteers (four men, three women; aged 26 +/- 4 years) participated in three experiments, performed in random order during 60 min continuous intra-duodenal infusion of either LCT (30 mL h(-1); 240 kcal h-1), equicaloric VLCT (30 mL h(-1); 240 kcal h(-1)) or MCT in equimolar (15 mL h(-1); 113 kcal h(-1)) and equicaloric amount (30 mL h(-1); 225 kcal h(-1)). Basal and stimulated SMA blood flow were measured by Doppler ultrasonography. At regular intervals blood samples were taken for measurement of plasma cholecystokinin (CCK) and plasma peptide YY (PYY). Basal SMA blood flow volumes were not significantly different among the LCT, VLCT and MCT experiments (426 +/- 135, 460 +/- 114 and 503 +/- 177 mL min(-1), respectively). The SMA flow increased significantly (P < 0.05) during fat infusion but was significantly higher during LCT (1460 +/- 692 mL min-1) compared with VLCT (1061 +/- 384 mL min-1), MCT 15 mL h(-1) (870 +/- 286 mL min(-1)) and MCT 30 mL h-1 (904 +/- 223 mL min(-1)). Plasma CCK levels increased significantly (P < 0.05) during LCT and VLCT but not during MCT infusion. No correlation was found between SMA flow and plasma CCK levels (r = 0.27; P = 0.2) The SMA blood flow in response to triglycerides is dependent on fatty acid chain length. This chain length-dependent blood flow response is, however, not linear and is not related to plasma CCK levels.