Plasma somatostatin-like immunoreactivity in depancreatized dogs

The present study was designed to determine the D cell response to ingested nutrients in totally depancreatized dogs. Basal levels of somatostatin-like immunoreactivity (SLI) averaged 135 ± 12 pg/ml in 7 depancreatized dogs and 146 ± 10 pg/ml in 30 controls (P = NS). In 7 conscious depancreatized dogs, an intragastric casein hydrolysate load elicited a small but significant rise of 20 pg/ml in peripheral venous plasma SLI levels during the first 60 min (P < 0.02); the incremental SLI (sum of the increments) during this period was 103 ±31 pg/ml, significantly less than the 278 ± 60 pg/ml in the normal control dogs (P < 0.05). In contrast to normal dogs, SLI did not rise in the depancreatized dogs in response to a fat-rich meat meal. After a liver meal, SLI levels rose by 30–40 pg/ml (P = NS) compared to the 80 pg/ml rise in the normal dogs. Gastric vein SLI levels were measured during laparotomy in six depancreatized and five control dogs after an intragastric load of casein hydrolysate. Antral vein SLI levels did not differ significantly in the two groups, but, in contrast to a substantial rise in the control animals, fundic vein SLI levels decreased in the depancreatized dogs. The incremental fundic vein SLI level in the depancreatized dogs was -2562 ± 2345 pg/ml compared to +14990 ± 330 pg/ml in the controls (P < 0.001). It is concluded that the postprandial rise in SLI in peripheral venous plasma is attenuated or abolished in totally depancreatized dogs and that this is due both to the absence of pancreatic SLI and to the reduction of the postprandial fundic SLI response.