EFFECT OF INSULIN IN CONJUNCTION WITH GLUCOSE, AMINO-ACIDS AND POTASSIUM ON NET METABOLISM OF GLUCOSE AND AMINO-ACIDS IN THE GOAT MAMMARY-GLAND

The hyperinsulinaemic euglycaemic insulin clamp technique was used to study the effect of insulin on the arterio-venous concentration differences of glucose and amino acids across the mammary gland in dairy goats. Insulin was given in conjunction with K to prevent insulin hypokalaemia. Appropriate amino acid infusion was used to blunt insulin-induced hypoaminoacidaemia or to create hyperaminoacidaemia and maintain this state under insulin treatment. Hyperaminoacidaemia alone only stimulated mammary leucine uptake but did not significantly modify the net metabolism of other amino acids and glucose. Insulin infusion at physiological level in conjunction with glucose, KCl-NaCl and amino acids failed to alter mammary uptake of glucose and essential amino acids; occasional increase in arginine extraction and decrease in tyrosine extraction were exceptions. Thus these new experimental conditions did not reveal any galactopoietic effect of insulin.