The effect of high cervical cordotomy on portal vein plasma serotonin and 5-hydroxyindoleacetic acid levels in dogs with and without superior mesenteric artery occlusion.

: In ten dogs undergoing high cervical cardotomy, there was a statistically significant fall in plasma serotonin (5-HT) levels in portal vein blood; no further change in plasma 5-HT occurred after superior mesenteric artery (SMA) occlusion, which is an effective stimulus for 5-HT release. In five dogs undergoing high cervical corotomy with no SMA occlusion, there was a comparable fall in portal vein plasma 5-HT levels. The 5-hydroxyindoleacetic acid (5-HIAA) values in portal vein blood in the two groups of dogs above fell to comparable levels. These findings indicate (1) that maintenance of the normal plasma 5-HT level in portal vein blood in this experimental model is dependent on the integrity of the spinal cord and (2) that SMA occlusion in animals with a high cervical cordotomy does not result in further changes in the plasma 5-HT level in portal vein blood.