EFFECT OF ESSENTIAL FATTY-ACID DEFICIENCY ON G-PROTEINS, CAMP-DEPENDENT PROTEIN-KINASE ACTIVITY AND MUCIN SECRETION IN THE RAT SUBMANDIBULAR SALIVARY-GLANDS

Studies were conducted to determine whether beta-adrenergic cell signa lling is altered in submandibular salivary glands (SMSG) is essential fatty acid (EFA) deficiency. Three groups of rats were fed diets which were deficient in EFA (EFAD), marginally deficient in EFA (MEFAD) or contained sufficient amount of EFA (Control). Rats were killed after 2 0 wk on diets, SMSG were dissected out and cyclic AMP-dependent protei n kinase (PKA) activity was measured. The specific enzyme activities w ere higher in the homogenates and supernatant fractions of the gland f rom EFAD and MEFAD rats compared with the controls. The relative level s of guanine nucleotide-binding regulatory proteins (Gs and Gi) were a lso measured in the SMSG membranes of rats fed the 3 diets. The levels of Gs were significantly higher in the EFAD and MEFAD groups than in the controls. No significant differences were observed in the secretio n of trichloroacetic acid-phosphotungstic acid (TCA-PTA) precipitable glycoproteins from the SMSG slices among the 3 dietary groups.