Arteriovenous differences of amino acids across the mammary glands of lactating rats are diminished when the rats are starved for 24 h. When 24 h-starved rats were refed for 2 1/2 h, the arteriovenous differences of amino acids returned to values similar to those found in well-fed rats. In order to find a possible explanation for these rapid changes, we tested the effect of ketone bodies on ami...

Previous studies have shown that the metabolism of acetone and acetate by the photosynthetic bacterium, Rhodopseudomonas gelatinosa, requires either light or oxygen as a source of energy (1, 2). The studies also showed that the cleavage of acetoacetate to acetat.e did not require an external source of energy. These observations are consistent with the known thermodynamic properties of the react...

The rates of conversion of D-(-)-3-hydroxy[3-14C]butyrate, [3-14C]acetoacetate, [6-14C]glucose and [U-14C]glutamine into 14CO2 were measured in the presence and absence of alternative oxidizable substrates in intact dissociated cells from the brains of young and adult rats. When unlabelled glutamine was added to [6-14C]glucose or unlabelled glucose was added to [U-14C]glutamine, the rate of 14C...

The existence of acetoacetyl-CoA synthetase in rat brain cytosol is reported. The coupling of this enzyme with cytosolic acetoacetyl-CoA thiolase can provide acetyl-CoA for lipogenesis and cholesterol synthesis without the need for mitochondrial participation. This new route for acetoacetate utilization may be important in developing brain.

BACKGROUND Standardized calibration does not change a creatinine measurement procedure's susceptibility to potentially interfering substances. METHODS We obtained individual residual serum or plasma samples (n = 365) from patients with 19 different disease categories associated with potentially interfering substances and from healthy controls. Additional sera at 0.9 mg/dL (80 μmol/L) and 3.8 ...

Transport of lactate, pyruvate and the ketone bodies acetoacetate and beta-hydroxybutyrate, is mediated in most mammalian cells by members of the monocarboxylate transporter family (SLC16). A conserved signature sequence has been identified in this family, which is located in the loop between helix 4 and helix 5 and extends into helix 5. We have mutated residues in this signature sequence in th...

To determine whether norepinephrine could subserve a hormonal as well as a neurotransmitter function, norepinephrine was infused for 60 min into each of five normal young men in doses of 0.1, 0.5, 1.0, 2.5, and 5.0 microgram/min. After infusion, the plasma norepinephrine concentration fell with a mean (+/-SD) half-time of 2.4 +/- 0.7 min. The mean (+/-SD) norepinephrine metabolic clearance rate...

The intralobular distribution of metabolism was examined in the livers from rats with severe diabetic ketoacidosis (DKA), perfused at pH 6.8, and compared with that in livers from normal starved animals perfused at either pH 7.4 or 6.8. With lactate and palmitate as substrates, the perivenous uptake of periportally synthesized glucose seen in normal livers at pH 7.4 was abolished during DKA; in...

Flavin and pyridine nucleotide fluorescence was continuously monitored from the surface of the hemoglobin-free, perfused rat liver with the use of a new double fluorometer. In response to anoxia or after addition of inhibitors of the respiratory chain, the fluorescence intensity excited at 436 rnk decreased, while that excited at 366 rnb increased, representing reduction of flavin and pyridine ...