Cholinergic regulation of pancreatic polypeptide secretion in chronic renal failure

Secretion of pancreatic polypeptide (PP) is regulated mainly by cholinergic mechanisms and we have studied this in patients with chronic renal failure (CRF). Basal serum PP concentrations in 25 patients with CRF (401 +/- 80; 116-2100 pmol/l; mean +/- SEM and range) were significantly higher than in 65 normal subjects (33 +/- 2; 21-120 pmol/l, P less than 0.001). Ingestion of a standard test meal induced significantly larger increases in serum PP in 11 patients with CRF (304 +/- 45; 155-640 pmol/l) than in 11 normal subjects (140 +/- 33; 51-440 pmol/l, P less than 0.005). Insulin-hypoglycaemia (0.1 U/kg i.v.) provoked similar increases in serum PP in five patients with CRF (404 +/- 79; 170-665 pmol/l) as in five normal subjects (449 +/- 92; 180-706 pmol/l). Administration of atropine (1 mg i.v.) did not normalize the elevated basal serum PP concentrations in five patients with CRF. On the other hand, administration of the same dose of atropine 60 min after ingestion of food decreased postprandial serum PP levels to basal values within one hour both in five patients with CRF and in six normal subjects. Sephadex G-50 column chromatography of basal, postprandial and post-atropine sera from three patients with CRF revealed at least three different molecular forms. The PP peak coeluting with the 4200 molecular weight human PP standard comprised more than half of total PP immunoreactivity and was the only peak to be influenced by feeding or atropine. We conclude that in patients with CRF, PP secretion stimulated by cholinergic mechanisms is normal.(ABSTRACT TRUNCATED AT 250 WORDS)