Physiological studies of exocrine pancreatic secretion in conscious rats. 6th communication: steady-state adaptation to different food composition.

In conscious rats provided with appropriate indwelling catheters the steady-state adaptation of digestive enzymes in pancreatic juice is investigated in relation to different food composition. Six isocaloric diets with different composition of carbohydrates (5-70%), proteins (10-57%) and fat (0-38%) are applied for two weeks before operation and also afterwards. The parameters determined are: flow-rate and total protein concentration of pancreatic juice, enzyme-separation by PAA-Gel-Electrophoresis and quantitative analysis of amylases I and II, lipase, chymotrypsins I and II and trypsin. The specific enzymatic activity, characterized by the enzyme fraction in per cent of total protein can be described best as a linear function of the corresponding nutrient portion (%) in the food. (Coefficient of linear regression mostly r = 0.98%). The regression lines for the sum of both amylases and all proteases are parallel to each other (y = 0.45x + b). Lipase activity is also linearly increasing with fat in food having a much smaller slope (y = 0.16x + b). The regression lines (y = ax + b) intersect with the ordinate at different points (section b), characterizing the "basal" secretion of pancreatic enzymes without any substrate in food. b (in %) for amylase I = 3.14, amylase II = 0.7 !, total proteases = 12.5 and lipase = 13.6. The regularity of inherent laws governing adaptation of pancreatic enzyme production and secretion to food composition allow to predict the prospective enzymatic secretion pattern for any given food composition.