Some adrenomimetic drugs affecting lipolysis in human adipose tissue in vitro

In human adipose tissue in vitro, dose-response curves were followed for different adrenomimetics releasing free fatty acids and glycerol into an albumin-containing medium. Phenylephrine, salbutamol and t-butyl-norsynephrine produced lipolytic actions whose maximum did not exceed 20% of the maximal isoproterenol lipolysis. Phentolamine (1 x 10(-5) M) did not potentiate the effect of any of these drugs. When using salbutamol or t-butyl-norsynephrine for antagonizing isoproterenol actions, typical antagonism was found. The parallel shift of the isoproterenol curves showed pA2 values 5.8 for salbutamol and 5.7 for t-butyl-norsynephrine. Comparison of human and rat adipose tissue reactivity shows identical affinities of the drugs studied in both tissues, but related to isoproterenol, diminished intrinsic activities of salbutamol and t-butyl-norsynephrine in human adipose tissue.