Prostaglandin E₂ and α₂ adrenoceptor agonists inhibit the pentose phosphate shunt in pancreatic islets

Glucose utilization in isolated pancreatic islets of the rat was inhibited by prostaglandin (PG) E₂ and the α₂ adrenoceptor agonist, clonidine, to a similar extent; other prostaglandins did not affect glucose utilization. Islet oxidation of [1-¹⁴C]glucose and [6-¹⁴C]glucose demonstrated that the pentose phosphate shunt was inhibited by PGE₂ and clonidine. Pertussis toxin antagonizes the effects of clonidine and PGE₂ on total glucose utilization and pentose phosphate shunt activity. The results suggest that PGE₂ and α₂ adrenoceptor agonists may regulate glucose metabolism through similar transduction mechanisms, and that a guanine nucleotide binding regulatory (G) protein modulates certain metabolic effects of prostaglandins and adrenergic agonists.