ISSN:
1432-1912
Keywords:
Lipolysis
;
Adenyl Cyclase
;
Phosphodiesterase
;
Glucocorticoids
;
Cyclic AMP
;
Cortisone
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The effects of adrenalectomy and cortisone replacement in rats on the activities of adenyl cyclase and phosphodiesterase in homogenates of isolated fat cells and on the accumulation of cyclic 3′,5′-AMP in intact cells were studied. 1. Adrenalectomy caused a decrease in the activity of norepinephrine- and fluoride-stimulated adenyl cyclase in homogenates of isolated fat cells. This decrease was not significantly reversed by pretreatment of the animals with cortisone in vivo. 2. Adrenalectomy caused an increase in the activity of phosphodiesterase. This increase was not reversed by pretreatment of the animals with cortisone for 4 h in vivo but was reversed after 18 h. Incubation of cells from adrenalectomized animals with cortisone in vitro caused no change in phosphodiesterase activity. 3. The incorporation of prelabelled nucleotides into cyclic 3′,5′-AMP was significantly reduced in intact cells from adrenalectomized rats. Pretreatment of the animals with cortisone in vivo for 4 h completely restored the ability of the cells to accumulate radiolabelled cyclic 3′,5′-AMP upon stimulation by norepinephrine. The experiments underline the difficulties in comparing activation patterns of enzymes under optimal conditions with those occurring in the intact cell. The nature of the lesion in lipolysis caused by adrenalectomy and the reversal of this lesion by cortisone replacement can be demonstrated in the intact cell only.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00501418
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