Negative Controls of Dog Thyroid Adenylate Cyclase Cyclic AMP System

Cyclic AMP content, adenylate cyclase (EC 4.6.1.1) activity and phosphodiesterase I (EC 3.1.4.1) activity of the hind leg skeletal muscle and cardiac muscle in 60- and 150-day-old normal and myopathic (UM-X7.1) hamsters were examined. In 60-day-old myopathic animals, cardiac cyclic AMP levels were higher and phosphodiesterase I activity was lower, without any changes in the basal adenylate cyclase activity, whereas in 150-day-old myopathic hamsters, cardiac cyclic AMP and basal adenylate cyclase activity were lower, without any changes in the homogenate phosphodiesterase I activity. On the other hand, basal adenylate cyclase and phosphodiesterase I activities in the skeletal muscle homogenate from 60- and 150-day-old myopathic animals were not different from the normal values but the skeletal muscle cyclic AMP levels were significantly less in 60-day-old myopathic hamsters only. The plasma cyclic AMP levels in 60-day-old myopathic hamsters, unlike 150-day-old myopathic animals, were higher than the normal. Although these results reveal differences in myopathic cardiac and skeletal muscles, it is concluded that changes in adenylate cyclase – cyclic AMP system in myopathy are dependent upon the degree of disease.

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Histamine receptors and cyclic AMP

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y80-155 ◽

1980 ◽

Vol 58 (9) ◽

pp. 1023-1030 ◽

Cited By ~ 17

Author(s):

John H. McNeill

Keyword(s):

Adipose Tissue ◽

Gastric Mucosa ◽

Cyclic Amp ◽

Adenylate Cyclase ◽

Histamine Receptors ◽

Rat Uterus ◽

Receptor Stimulation ◽

Amp System ◽

Organ Systems ◽

Stimulation Of

The identification and characterization of histamine receptors in the organ systems of various species has been made possible in recent years by the introduction of relatively selective agonists and antagonists of H1 and H2 receptors. H2 receptors have now been clearly demonstrated in gastric mucosa, heart, rat uterus, brain, and adipose tissue. Less well-defined H2 receptor systems have also been described in the vasculature, bronchioles, and other smooth muscles as well as in the thyroid gland and lymphocytes. In tissues where it has been examined a close correlation between H2 receptors and the adenylate cyclase – cyclic AMP system has been found. With the exception of the central nervous system stimulation of H1 receptors does not seem to be involved with cyclic AMP. In the case of the brain the H1 receptor stimulation of adenylate cyclase can be differentiated from H2 receptor stimulation of the enzyme by the use of blocking agents and by the fact that the H1 receptor response is enhanced in the presence of adenosine. Studies of the involvement of histamine with the adenylate cyclase – cyclic AMP system have been concentrated on such tissues as gastric mucosa, heart, rat uterus, brain, and adipose tissue. The present review will concentrate on the literature concerning those tissues.

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Consequences of hormone-induced desensitization of adenylate cyclase in intact cells

Biochemical Journal ◽

10.1042/bj1880169 ◽

1980 ◽

Vol 188 (1) ◽

pp. 169-174 ◽

Cited By ~ 23

Author(s):

S Swillens ◽

E Lefort ◽

R Barber ◽

R W Butcher ◽

J E Dumont

Keyword(s):

Energy Consumption ◽

Cyclic Amp ◽

Adenylate Cyclase ◽

Large Energy ◽

Intact Cells ◽

Amp System ◽

Good Compromise ◽

Highly Efficient ◽

Theoretical Considerations

A hypothesis on the role of the hormone-induced desensitization of adenylate cyclase is proposed. It is suggested that the desensitization process could provide the cell with a highly efficient cyclic AMP system for transmitting hormone stimulus without requiring a large energy consumption. Theoretical considerations show that in fact the desensitization phenomenon allows the cyclic AMP system to present a good compromise between the efficiency and economy requirements of the cells.

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Role of the adenylate cyclase system in altered insulin release from islets of Langerhans of aging rats

Acta Endocrinologica ◽

10.1530/acta.0.0960222 ◽

1981 ◽

Vol 96 (2) ◽

pp. 222-226 ◽

Cited By ~ 5

Author(s):

Loren G. Lipson ◽

Michael J. Bush ◽

Gretchen E. Tietjen ◽

Aeree Yoon

Keyword(s):

Cyclic Amp ◽

Adenylate Cyclase ◽

Insulin Release ◽

Islets Of Langerhans ◽

Male Rats ◽

Adenylate Cyclase System ◽

Control Male ◽

Aging Rats ◽

Amp System ◽

Old Rats

Abstract. In attempting to understand the causes of the hyperglycaemia observed in aging populations and to determine the mechanism(s) for the diminished in vitro insulin release from islets of Langerhans of older rats, the adenylate cyclase-cyclic AMP system was studied in isolated islets from 12 month old and 2½ month old (control) male rats to determine its role in this altered insulin secretion. Islets of Langerhans were isolated by collagenase digestion and then either incubated in the presence of low or high concentrations of glucose for studies of insulin release or were sonicated and assayed for determinations of activities of adenylate cyclase and phosphodiesterase. Insulin release was identical from islets of 12 month old and 2½ month old rats to 2.8 mm D-glucose, while in the presence of 16.7 mm D-glucose, insulin release was decreased by 33% (P < 0.02) from islets of the older animals. Adenylate cyclase activity was diminished by 60% (P < 0.005) from the 12 month old rats as compared with islets from the 2½ month old controls, while low Km phosphodiesterase activity was similar in islets from both groups of animals. From these studies it appears that the adenylate cyclase-cyclic AMP system may play a role in the altered insulin release from islets of aging rats.

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