Effects of alpha- and beta-adrenergic blockers on binding of thyrotrophin to fat cell membrane.
Alpha- (phentolamine) and beta-adrenergic blocking agents (propranolol) and quinidine similarly enhance the specific binding of TSH to the guinea pig fat cell membranes over the concentration range of 2 X 10(-4) to 4 X 10(-3) M, increasing the binding affinity of TSH to the membranes. The percentage bound increased from 8% in the absence of agents to 32% (phentolamine), 29% (propranolol) and 24% (quinidine), respectively in the presence of these agents (1.5 X 10(-3) M). Each minimal detectable quantity of TSH was approximately 10 microU per tube in the presence of these agents (10(-3) M) as compared to 100 microU per tube in their absence. Both phentolamine and propranolol appeared to enhance the TSH binding to fat cell membranes through membrane-active, non-specific effects besides their alpha- and beta-adrenergic blocking activities.
D000273:Adipose Tissue / Q000378:metabolism*; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism*; D006168:Guinea Pigs; D006801:Humans; D010646:Phentolamine / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D011802:Quinidine / Q000494:pharmacology*; D011869:Radioligand Assay; D011956:Receptors, Cell Surface / Q000187:drug effects*; D013972:Thyrotropin / Q000378:metabolism*
D000779:Anesthetics, Local; D000889:Anti-Arrhythmia Agents; D011956:Receptors, Cell Surface; D013972:Thyrotropin; D011433:Propranolol; D011802:Quinidine; D010646:Phentolamine