Acute loading with proteins from different sources in healthy volunteers and diabetic patients

To evaluate the effects of protein loading on glomerular filtration rate (GFR), urinary excretion rate of albumin (AER), and plasma concentration of amino acids, 10 healthy volunteers and six diabetics were studied before and after eating tuna fish, egg white, cheese, or tofu. Furthermore, to study the possible role of glucagon, growth hormone (GH), atrial natriuretic peptide (ANP), or kallikrein in the responses of GFR, these substances were measured before and after protein loading. GFR increased significantly (p less than .001) after ingestion of tuna fish. No significant differences were seen between the GFR before and that after ingestion of the other foods. AER was unchanged following protein loading. Plasma concentrations of alanine, glycine, and arginine increased to a greater degree after ingestion of tuna fish than after digestion of the other foods. This result suggests that the response of GFR after protein loading may differ from one protein to another, and that these responses may not be directly mediated by glucagon, GH, ANP, or kallikrein.