Figure 6. (A-C) Levels of insulin in transplanted STZ diabetic Lewis rats (n = 4) measured during intravenous glucose tolerance testing. Data are shown and mean ± SE. D Left: Chromatogram (top) and product ion mass spectrum (bottom) of porcine insulin (precursor ion [M+5H]5+m/z 1156.3) extracted from 2 ml plasma obtained 5 min after IV glucose administration to a STZ-diabetic transplanted rhesus macaque. The retention time and diagnostic product ions derived from the 5-fold charged precursor ion unambiguously identify porcine insulin. (D) Right: chromatogram (top) and product ion mass spectrum (bottom) of human/macaque insulin (precursor ion [M+5H]5+m/z 1162.3) extracted from 1 ml of non-diabetic rhesus macaque plasma. The retention time and diagnostic product ions derived from the 5-fold charged precursor ion unambiguously identify human/macaque insulin. Reproduced with permission.13,15