Five peaks of cyclic AMP-binding activity could be resolved by DEAE-cellulose chromatography of bovine adrenal-cortex cytosol. Two of the binding peaks co-chromatographed with the catalytic activities of cyclic AMP-dependent protein kinases (ATP-protein phosphotransferase, EC 2.7.1.37) of type I or type II respectively. A third binding protein was eluted between the two kinases, and appeared to...

The present study was undertaken to investigate the role of cyclic AMP and cyclic GMP in the regulation of the contraction-relaxation cycle in isolated smooth muscle cells from guinea pig taenia caeci. The contraction of isolated smooth muscle cells induced by both caffeine (4 X 10(-3) M) and carbachol (10(-4) M) consisted of an initial activation phase and a following spontaneous relaxation ph...

In developing Dictyostelium discoideum cells, binding of cyclic AMP to the chemotactic receptor has been shown to oscillate. These oscillations represent cycles of activation, adaptation and deadaptation of the cyclic AMP receptor system. We studied the molecular basis of these oscillatory changes in cyclic AMP receptor binding. We developed a rapid method of lysing cells during the course of t...

An impro&d, simplified procedure is described for the isolation of liver cells from rat or chicken. Livers were perfused in sifu and then incubated in a solution of collagenase and hyaluronidase. Greater than 50 % of the liver mass was converted into a suspension of intact parenchymal cells which excluded a vital stain and were undamaged when viewed with the electron microscope. The cells activ...

1. A wide range of purine bases, nucleosides and cyclic nucleotides were shown to induce betacyanin synthesis in Amaranthus seedlings. 2. The induction of pigment by benzyladenine, dibutyryl cyclic AMP or cyclic AMP was not potentiated by aminophylline. Aminophylline was shown to inhibit Amaranthus cyclic AMP phosphodiesterase activity. 4. Incubation of seedlings with aminophylline inhibited th...

The concentration of adenosine 3',5'-monophosphate (cyclic AMP) and the activity of adenylate cyclase were determined for the first time in conjuncation with cyclic 3',5'-nucleotide phosphodiesterase (phosphodiesterase) during the growth cycle of Tetrahymena pyriformis. High levels of cyclic AMP observed during early exponential and late stationary phases were associated with elevated adenylate...

Acetazolamide, an inhibitor of the enzyme carbonic anhydrase, increased the urinary excretion of cyclic AMP in normal and parathyroidectomized rats. The increase was greater in rats with intact parathyroid glands than in parathyroidectomized rats. This rise in the urinary excretion of cyclic AMP was not due to an increase in urine flow or a change in urine pH. Furosemide caused an increase in u...

In the presence of DL-alanine intracellular cyclic AMP in nonproliferating cells of Brevibacterium liquefaciens increased rapidly to the maximum level of approximately 180 muM, and extracellular cyclic AMP increased to 100 muM within 4 hr at 25 degrees . Adenylate cyclase (EC 4.6.1.1) induction was not observed during this incubation. The concentration of pyruvate in the total culture increased...

The purpose of this study was to examine the mechanisms underlying adrenergic-cholinergic antagonism in ventricular myocardium. Myocardial contractility, cyclic adenosine monophosphate (AMP) levels, and cyclic guanosine monophosphate (GMP) levels were measure in isolated guinea pig ventricles after treatment with various inotropic agents given alone and simultaneously with acetylcholine. Acetyl...

Renal vein renin activity was measured by bioassay of plasma obtained from anesthetized dogs during renal arterial infusion of sympathomimetic amines, cyclic AMP, and other nucleotides. Renin secretion was calculated as the product of renal blood flow and the arterial-renal venous renin difference. Infusion of cyclic AMP significantly increased renin secretion, while administration of ATP, ADP,...