title: Effects of thyroid status on membrane-bound low Km cyclic nucleotide phosphodiesterase activities in rat adipocytes.
abstract: Adipocyte membranes from hypothyroid rats showed increased low Km cAMP phosphodiesterase activity compared to normals, provided that the subcellular fractionations were done in isotonic, as opposed to hypotonic, buffers. The enhanced cAMP phosphodiesterase activity in hypothyroid membranes was nearly normalized by incubation with a 10-fold excess of cGMP. Preincubation of hypothyroid adipocytes with cGMP also restored to normal the blunted lipolytic response to micromolar concentrations of epinephrine. DEAE-Sephacel chromatography of detergent-solubilized membrane-bound cAMP phosphodiesterase showed a 2.5-fold enhancement in hypothyroid membranes of a form of the enzyme that was completely inhibited by cGMP; the enzymatic elution profiles of the soluble fractions showed no difference between normal and hypothyroid fat pads. The results suggest a possible regulatory role of cGMP in adipocytes in the hypothyroid state.
authors.forename: A
authors.initials: A
authors.lastname: Goswami
authors.forename: I N
authors.initials: IN
authors.lastname: Rosenberg
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000378:metabolism*; D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D006152:Cyclic GMP / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D007037:Hypothyroidism / Q000201:enzymology*; D007700:Kinetics; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D051381:Rats; D013961:Thyroid Gland / Q000502:physiology*
chemical_list: D003995:Dibutyryl Cyclic GMP; D003994:Bucladesine; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D006152:Cyclic GMP; D004837:Epinephrine