Fig S1 Dilution parallelism of glucagon and PP.tiff

Dilution parallelism of glucagon (S1A) and pancreatic polypeptide (PP, S1B) in feline plasma, as measured by the MILLIPLEX® Human Metabolic Hormone Magnetic Bead Panel. Samples with high hormone concentrations for serial dilutions were obtained from multiple experiments, including samples with increased endogenous glucagon and PP (after IV arginine stimulation during hyperglycemia, post prandial samples, and samples obtained after a glucagon receptor antagonist (MK3577) administration and increased exogenous glucagon (after rectal administration of human recombinant glucagon). There was no difference in serial dilution results between samples with either increased exogenous or endogenous glucagon and the results are reported jointly. For glucagon, linear regression results for expected versus observed results in serial dilutions were R2 = 0.98, slope = 0.8 ± 0.03 (p < 0.0001, CI = 0.75 – 0.87) and a Y intercept = 16.3 ± 12.9 (Figure S1A). For PP, linear regression results for expected versus observed results in serial dilutions were R2 = 0.97, slope = 1.1 ± 0.09 (P < 0.0001, CI = 0.91 – 1.35) and a Y intercept = -1.0 ± 1.8 (Figure S1B). However, samples with high (641 - 2100 pg/mL) PP concentrations were not available (highest was 338.6 pg/mL) so the linearity of the assay was only assessed for PP in the low-to-mid range.