Systemic arterial pressure, jejunal perfusion pressure, and jejunal blood flow were measured in eight autoperfused canine jejunum preparations (5 dogs) before and during local intra-arterial infusion of physiological doses of secretin (18.5 pM), neurotensin (233 pM), and cholecystokinin octapeptide (CCK-8, 30 pM). Intra-arterial infusion of secretin, neurotensin, or CCK-8 alone did not affect either systemic or jejunal arterial pressures. Likewise, jejunal blood flow was not significantly altered by secretin (3 +/- 3%), neurotensin (-5 +/- 4%), or CCK-8 (-5 +/- 5%). Even when all three hormones were infused simultaneously, jejunal blood flow was not altered (2 +/- 3%). However, when infused at rates that produced calculated arterial blood levels some 100 times greater than those reported as "postprandial," each hormone alone, as well as in combination, produced marked increases in jejunal blood flow. Secretin, neurotensin, and CCK-8 increased blood flow by 34 +/- 8, 31 +/- 11, and 24 +/- 5%, respectively. Simultaneous infusion of all three hormones increased jejunal blood flow by 47 +/- 11%. These data suggest that, either alone or in combination, secretin, neurotensin, and CCK-8 are not of quantitative importance in regulating jejunal blood flow during the postprandial state. However, higher (presumably pharmacological) blood levels of these hormones do significantly elevate jejunal blood flow.