Two distinct adaptive responses in the synthesis of exocrine pancreatic enzymes to inverse changes in protein and carbohydrate in the diet
Schick, J.; Verspohl, R.; Kern, H.; Scheele, G.
American Journal of Physiology 247(6 Pt 1): G611-G616
1984
ISSN/ISBN: 0002-9513 PMID: 6507618 Document Number: 236041
Rates of synthesis of 16 pancreatic exocrine proteins, tissue concentrations of amylase, trypsinogen and chymotrypsinogen, and morphological assessment of pancreatic acinar cells were studied in male Wistar rats in response to inverse changes in protein and carbohydrate in the diet, given for 12 days. During adaptation to diets containing normal protein (22%) or increased protein (30, 45, 64 and 82%) and correspondingly decreased carbohydrate, amylase and most protease zymogens were synthesised in direct proportion to the nutritional substrates carbohydrate and protein, respectively, in the diet. With increases in dietary protein, anticoordinate patterns of response in the synthesis of exocrine isoenzymes were observed. During adaptation to diets containing normal protein (22%) or decreased protein (0 or 10%) and correspondingly increased carbohydrate, amylase and most protease zymogens were synthesised in inverse proportion to nutritional substrates in the diet. When a protein-free diet was given, coordinate and anticoordinate synthesis patterns were related to isoelectric points of exocrine isoenzymes. Synthesis of acidic proteins, representing 45.6% of exocrine proteins synthesised in normal laboratory dietary conditions, increased to 95% after a protein-free diet was given for 12 days. This response in exocrine pancreatic protein synthesis to a protein-free diet, previously uncharacterized, seems to be genetically regulated and represents an adaptation important to survival during protein deprivation.