ISSN:
1432-2013
Schlagwort(e):
Rat Kidney
;
Isolated Tubules
;
Cyclic Adenosine 3′:5′-Monophosphate
;
Parathyroid Hormone
;
Norepinephrine
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Medizin
Notizen:
Summary Isolated rat kidney cortex tubules were used as a model system to study the hormonal regulation of cyclic adenosine-3′: 5′-monophosphate (cAMP) levels in vitro. When incubated over 15 min, parathyroid hormone increased cAMP levels 4-fold in the absence of inhibitors of cAMP phosphodiesterase. Norepinephrine in a concentration of 5·10−7 M which had itself no effect on cAMP levels under this condition, inhibited the effect of parathyroid hormone by 50%. This effect of the catecholamines could be completely abolished by the addition of an α-receptor blocking agent, phentolamine. The addition of an inhibitor of cAMP phosphodiesterase, in a concentration sufficient to prevent the breakdown of extratubular cAMP, potentiated hormone effects on cAMP levels. The antagonism between catecholamines and parathyroid hormone on cAMP levels was however not abolished by this treatment. This indicated that catecholamines probably inhibited parathyroid hormone stimulated cAMP formation. Since most of the cAMP was found to be intratubular, it can be assumed that norepinephrine and parathyroid hormone interact in the same cell. Proximal tubular sodium reabsorption and renal gluconeogenesis are discussed as possible events of this hormone interaction.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00579947
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