Effect of Metals upon the Conversion of Adenosine Triphosphate to Adenosine 3′,5′-Monophosphate in Lipocytes ∗

Abstract

Summary

Investigations with isolated lipocytes were conducted concerning the effects of Mg, Ca, Zn, and K upon the formation of c-AMP-¹⁴C from ATP-¹⁴C. The Mg markedly increased the production of c-AMP-¹⁴C. The Ca stimulated a smaller increment, but reduced that caused by Mg. When the cells were preincubated with Ca, and then repeatedly washed with Tris-glycerophosphate buffer, no effect was produced by Mg unless EGTA was also used, suggesting a stronger affinity of the lipocytes for Ca than for Mg. A similar level of c-AMP-¹⁴C was found whether Ca was used alone, or in each combination tested with Mg, isopropylnorepinephrine, K, or insulin. The Zn markedly reduced the increments of c-AMP-¹⁴C when used alone or with Mg. The K alone had no effect and influenced the results with Ca and/or Mg relatively little. The NaF, used alone or with Ca, produced no changes, but caused tenfold increments with Mg. Isopropylnorepinephrine had no effect alone, or with Ca or Zn, but it produced marked additional increments when used with Mg. Insulin reduced very slightly the Mg action but did not affect the action of the other metals.