Formate metabolism in sheep

Abstract

glucose and free fatty acids in the whole animal, but the use of isotopically labelled substrates has allowed some parameters to be defined. SUMMARY 1. The rates of entry of glucose and acetate in fed and starved sheep were measured simultaneously by the constant infusion of labelled glucose and labelled acetate. 2. The entry of acetate after feeding was sufficiently constant to allow measurement of entry rates only during the period when a maximum concentration of rumen acetate was attained, which presumably coincided with maximum production and absorption of acetate. 3. The entry of endogenous acetate in sheep with emptied rumens was 40-50 % of the value for the total entry of acetate obtained in the same animals after feeding. Under conditions of normal acetate absorption, the entry of endogenous acetate accounted for about 25 % of the total entry. 4. Raised concentrations of blood glucose or acetate reduced the entry of endogenous acetate in sheep with emptied rumens, or in starved sheep. These results were consistent with the hypothesis that the oxidation of free fatty acids contributes substantially to the entry of endogenous acetate in sheep. This investigation was made possible by the generous support of the Australian Wool Research Committee. Mr J. Roberts and Mrs J. Musgrave gave valuable technical assistance.

In Vivo Kinetics of Formate Metabolism in Folate-deficient and Folate-replete Rats

“…As far as we are aware, there is only one study that examined formate whole-body kinetics. This study (9) reported rates of formate appearance of ϳ2-4 mg/kg/h (ϳ45-90 mol/kg/h) in sheep. There appears to be no study of whole-body formate kinetics in situations where plasma formate levels are elevated.…”

Formate: an essential metabolite, a biomarker, or more?

“…[ 10 ] motivated Annison and White [ 11 ] to conduct the first and only available constant-infusion study of formate turnover. They reported a production rate of approximately 4.6 mg (100 μ mol)/kg/h; a rate that is very similar Unauthenticated Download Date | 5/12/18 7:28 PM…”

“…Annison [ 9 ] showed that formate represents 10% -30% of the total volatile fatty acids in the blood of numerous animals, but most importantly, that its concentration is similar in goats, cattle, horses, dogs, cats and humans. This observation, combined with that of formate production by perfused goat liver preparation by McCarthy et al[ 10 ] motivated Annison and White [ 11 ] to conduct the first and only available constant-infusion study of formate turnover. They reported a production rate of approximately 4.6 mg (100 μ mol)/kg/h; a rate that is very similar Unauthenticated Download Date | 5/12/18 7:28 PM…”

Importance of the Effective Strong Ion Difference of an Intravenous Solution in the Treatment of Diarrheic Calves with Naturally Acquired Acidemia and Strong Ion (Metabolic) Acidosis

“…32 The strong ion formate is metabolized primarily to CO 2 (thereby increasing SID), but formate does not appear to be metabolized to HCO 3 À . [46][47][48] Another clinically important issue is whether effective volume expansion by administering an isotonic solution with sodium as the only cation is sufficient to correct the metabolic acidosis in diarrheic calves. Only a few studies have been conducted previously in dehydrated diarrheic calves comparing the alkalinizing effect of different sodium containing salts.…”

“…The effective SID is not equivalent to bicarbonate because sodium formate is alkalinizing . The strong ion formate is metabolized primarily to CO 2 (thereby increasing SID), but formate does not appear to be metabolized to HCO 3 − …”