We determined the effect of alpha-adrenergic receptor stimulation on cyclic adenosine monophosphate (cyclic AMP) concentrations in isolated myocytes derived from adult rat hearts and in isolated perfused rat hearts. Activation of alpha-adrenergic receptors with either phenylephrine (10(-8) M to 10(-6) M) or epinephrine (10(-8) M to 10(-6) M) plus propranolol (10(-6) M) resulted in a reduction i...

Three derivatives of cyclic AMP that are potentially useful as photo-affinity labels were synthesized. One of these derivatives is, upon photolysis, specifically incorporated into the cyclic AMP-binding site of rabbit muscle phosphofructokinase. The use of these derivatives in isolating and identifying cyclic AMP receptor sites is discussed.

Isolated liver cells from fasted female rats synthesized glucose in the presence of alanine, lactate, and pyruvate. Epinephrine, norepinephrine, and phenylephrine stimulated gluconeogenesis whereas isoproterenol and salbutamol had no effect on gluconeogenesis from lactate. Dand L-Propranolol had no effect on epinephrine-stimulated gluconeogenesis but blocked cyclic adenosine 3’:5’-monophosphate...

We determined the effect of a-adrenergic receptor stimulation on cyclic adenosine monophosphate (cyclic AMP) concentrations in isolated myocytes derived from adult rat hearts and in isolated perfused rat hearts. Activation of a-adrenergic receptors with either phenylephrine (10~ M to 10~ M) or epinephrine (10" M to 10~ M) plus propranolol (10 ' M) resulted in a reduction in cyclic AMP levels in...

We have studied cyclic adenosine 3',5'-monophosphate (cyclic AMP) concentrations in human peripheral blood lymphocytes after stimulation with phytohemagglutinin (PHA), isoproterenol, prostaglandins, and aminophylline. Purified lymphocytes were obtained by nylon fiber chromatography, and low speed centrifugation to remove platelets. Cyclic AMP levels were determined by a highly sensitive radioim...

The actions of certain lipolytic and antilipolytic agents were studied in isolated fat cells at the level of cyclic AMP. The following observations were made. Epinephrine (5.5 PM) produced small but significant changes in cyclic AMP levels in IO-min incubations while caffeine (1 111~) was without significant effect. In combination, epinephrine and caffeine acted synergistically, producing large...

The effects of thyroid-stimulating antibodies (TSAb) and of thyrotropin (TSH) were compared, on the generation of cyclic AMP and inositol phosphates (InsP), in human thyroid slices incubated in vitro, and on the Rapoport cyclic AMP bioassay. The TSAb positive sera were obtained from 19 patients with Graves' disease. In 14 experiments with the slices system, TSH significantly increased cyclic AM...

A spontaneously occurring rat adrenocortical carcinoma which produces corticosterone was maintained by transplantation. The carcinoma appeared to utilize corticosterone biosynthetic steps similar to those of the normal adrenal, but the tumor produced only about 1-10% as much corticosterone per unit tissue weight as nontumorous adrenal glands. The tumor demonstrated little or no increase in cort...

The effects of ischemia and anoxia on cardiac adenosine 3',5'-monophosphate (cyclic AMP) concentration, glycogen phosphorylase activity ratio (— 5'-AMP: + 5'-AMP), phosphorylase kinase activity ratio (pH 6.8:8.2), and myocardial contractility (left ventricular dP/dt) were studied in an open-chest rat heart preparation. Ischemia produced by termination of coronary blood flow increased cyclic AMP...

We studied the relationships between the positive inotropic effects of isoproterenol, increased frequency of contraction or paired electrical stimulation, and cyclic AMP concentration and phosphorylase activity in isolated guinea pig papillary muscles. The minimum concentration of isoproterenol (10 nM) that augmented isometric force development increased cyclic AMP concentration. However 100 nM...