Minimal glycerol phosphorylation and gluconeogenesis in the liver with 1,3PDO and 3HP. (A) In 13C NMR of glycerol C1&C3 and glycerol 3-phosphate (G3P) C1 from liver extracts, singlet (S) signals are from natural 13C abundance and they are detected in all hamsters. However, doublet (D) signals from [U–13C3]glycerol and [U–13C3]G3P are negligible in the liver with 1,3PDO and 3HP while they are strong in the liver without 1,3PDO and 3HP. (B) The concentrations of glycerol and G3P were unaltered, but their 13C enrichments were decreased in the liver with 1,3PDO and 3HP. (C) In 13C NMR of α-glucose C1, a singlet (S) reflects [1–13C1]glucose with natural abundance while a doublet (D) is from [1,2,3–13C3]glucose. The doublet reflects gluconeogenesis from [U–13C3]glycerol. (D) The concentrations of glucose in the liver and plasma were unchanged, but their 13C enrichments were reduced in the presence of 1,3PDO and 3HP. Abbreviations: DHAP, dihydroxyacetone phosphate, GA3P, glyceraldehyde 3-phosphate; open circle, 12C; black circle, 13C; ∗, p < 0.05; ∗∗, p < 0.001, n = 6–10 in each group.