Direct Antilipolytic Effect of Acidosis in Isolated Rat Adipocytes

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Abstract
The possibility that acidosis inhibits lipolysis indirectly by causing ionic shifts or by favouring the accumulation of an inhibitor has been tested in isolated fat cells. Lipolysis induced by 3 μM noradrenaline (NA) was inhibited by 40–60% and that induced by 1 mM theophylline (THEO) by about 75% when the pH was reduced to 6.6. Lipolysis induced by NA+THEO was inhibited by 20–30%. Changing the concentration of Ca++or Mg++did not alter the degree of inhibition. Reducing the K+‐ion concentration enhanced the inhibitory effect of low pH on lipolysis induced by NA or NA + THEO, whereas cyclic AMP accumulation was uninfluenced. Omitting glucose from the incubation medium caused a slight enhancement of pH‐induced inhibition of lipolysis (from 60 to 70%, p+ion concentration. The inhibitory effect of acidosis on various responses to β‐adrenoceptor stimulation may be caused by a decreased formation of cyclic AMP in turn caused directly by the decrease in pH.