The effects, in vivo, of epinephrine, glucagon, and dibutyryl cyclic adenosine 3',5'-monophosphate (cyclic AMP) on the glycogen content of rat heart and liver and, in vitro, upon adenylate cyclase activity in homogenates of rat heart and liver were determined during the latter third of gestation and the neonatal period. Hepatic glycogen was depleted by epinephrine, glucagon, and dibutyryl cycli...

Both basal and prostaglandin E1 (PGE1)-stimulated human platelet adenylate cyclase activity are inhibited by Na+ and other monovalent cations. Inhibition occurs when the cations are present in concentrations of 20 to 120 mM. Inhibition of basal activity by epinephrine requires the presence of GTP but not Na+. In the presence of epinephrine and GTP, Na+ further reduces basal activity, and the co...

Plasma membranes from bovine corpora lutea have been purified by sucrose density gradient centrifugation. The purified membranes, in addition to binding 1251-hCG, also possess hCGstimulated adenylate cyclase and Na-K-ATPase. The relative purification of 1251-hCG binding, adenylate cyclase and Na-KATPase on the basis of the specific activities in the whole homogenate were 7.8, 6.4 and 2.6, respe...

The effect of Ca and calmodulin has been studied on adenylate cyclase activity in homogenates of rat islets of Langerhans. EGTA had a stimulatory effect on the enzyme in accord with the known inhibitory effect of Ca. In contrast, the addition of Ca together with calmodulin is stimulatory and demonstrates the existence of a Ca-dependent adenylate cyclase in islets of Langerhans. It is suggested ...

An improved method for the isolation of rat pancreatic islets possessing adenylate cyclase responsive to various hormones and agents is described. The key step in this method, which yielded up to 500 islets per pancreas, involved pretreatment of rats with pilocarpine. This allowed depletion of zymogens from the exocrine pancreatic tissue and thus minimized the destruction of islet membranal str...

Deficient activity of the guanine nucleotide regulatory protein (G unit), an integral component of the membrane-bound adenylate cyclase complex, has been implicated as the biochemical lesion in many patients with pseudohypoparathyroidism (PHP) type I. In addition to renal resistance to parathyroid hormone in this disorder, there is decreased responsiveness of diverse tissues to hormones that ac...

Morphine inhibits adenylate cyclase (EC 4.6.1.1) activity of neuroblastoma times glioma hybrid cells. The inhibition is stereospecific and is reversed by the antagonist, naloxone. The relative affinities of narcotics for the opiate receptor agree well with their effectiveness as inhibitors of adenylate cyclase. Morphine-sensitive and -insensitive cell lines were found, and the degree of sensiti...

Forskolin acts primarily by activating the enzyme adenylate cyclase, which results in increased cyclic adenosine monophosphate (cAMP) in cells. Cyclic AMP belongs to a class of substances known as "second messengers" and is one of the most important cell-regulating compounds. Among its many roles, cAMP activates numerous other enzymes involved in diverse cellular functions. Hormones and neurotr...

Biochemical assays of adenylate cyclase activity were performed during the early phases of regeneration in Owenia fusiformis (Polychaete Annelid). The results indicate the existence of a strong stimulation in an early phase following trauma. This stimulation is then followed by periodic fluctuations exhibiting a diurnal rhythm correlated with the cell cycle. Adenylate cyclase activity is also s...