Extracellular ATP and UTP exert similar effects on rat isolated hepatocytes

1 Extracellular UTP and ATP show obvious similarities in their control of several metabolic functions of rat isolated hepatocytes. 2 They have a similar time‐course and concentration‐dependency for the activation of glycogen phosphorylase, the generation of inositol trisphosphate (IP3), the inhibition of glycogen synthase and the lowering of adenosine 3′: 5′‐cyclic monophosphate (cyclic AMP) levels. 3 There is a similar synergism of the nucleotides with glucagon in activating phosphorylase. 4 They undergo a similar inhibition by phorbol myristic acid of their glycogenolytic effect. 5 The ATP and UTP effect on IP3 levels are not additive. 6 It is tentatively concluded that UTP and ATP use a common receptor.