Adenylate cyclase and β-receptors in salivary glands of rats fed diets containing trans fatty acids

The effects of trans fatty acids on adenylate cyclase were determined in the submandibular salivary glands (SMSG) of rats fed diets containing 20% corn oil, 20% partially hydrogenated soybean oil (PHSBO) or 18% PHSBO + 2% corn oil. The fluoride- and isoproterenol-stimulated adenylate cyclase activities were higher in the SMSG from rats fed 20% PHSBO than in the control group fed 20% corn oil. The feeding of 2% corn oil with the diet containing 18% PHSBO resulted in a complete restoration of isoproterenol-stimulated and a partial restoration of fluoride-stimulated adenylate cyclase activity. There was no significant difference in the concentration of the beta-adrenergic receptor or in the receptor-binding affinity constants among the three dietary groups as measured by [3H]dihydroalprenolol (DHA)-binding. Higher fluorescence polarization of diphenyl hexatriene (DPH) was observed in SMSG membranes of rats fed diet containing 20% PHSBO than in the other two oils, suggesting that membrane fluidity may play a role in adenylate cyclase activity.