Effects of β-hydroxybutyrate and isoproterenol on lipolysis in isolated adipocytes from periparturient dairy cows and cows with clinical ketosis.

An in vitro model was used to investigate effects of β-hydroxybutyrate and isoproterenol (β-adrenergic receptor agonist) on lipolysis in isolated adipocytes from late pregnant and recently calved dairy cows (n=5) and cows with clinical ketosis (n=3). Incubation with 3.0 mmol/L β-hydroxybutyrate reduced lipolysis in isolated adipocytes. This inhibitory effect was lower in the first lactation week (47%±16%) compared with late pregnancy (71%±6.5%). Incubation with 0.3 μmol/L isoproterenol stimulated lipolysis in isolated adipocytes from periparturient dairy cows. Basal lipolysis resulted in non-esterified fatty acid to glycerol ratios in the incubation media of 2.0±0.23 in prepartum samples, 2.1±0.23 in the first lactation week and 2.2±0.09 in cows with clinical ketosis. β-Hydroxybutyrate reduced lipolysis by 45%±9.6% in isolated adipocytes from cows with clinical ketosis, indicating that impaired feedback of β-hydroxybutyrate may not play a role in the disease etiology.