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Catecholamine effect on cyclic adenosine 3':5'-monophosphate level in isolated catfish hepatocytes
L Brighenti1, A C Puviani, M E Gavioli
1Institute of General Physiology, University of Ferrara, Italy.
General and Comparative Endocrinology
|November 1, 1987
Summary
Catecholamines like epinephrine significantly boost cyclic adenosine 3':5'-monophosphate (cAMP) in catfish liver cells, primarily through beta-receptor activation. This suggests a complex role in regulating catfish glycogenolysis.
Area of Science:
- Comparative Endocrinology
- Cellular Physiology
- Biochemistry
Background:
- Catecholamines regulate metabolic processes in vertebrates.
- Understanding fish liver cell responses to catecholamines is crucial for comparative physiology.
- Previous studies indicated epinephrine and norepinephrine act via beta-receptors in catfish.
Purpose of the Study:
- To investigate the impact of various catecholamines on cyclic adenosine 3':5'-monophosphate (cAMP) levels in isolated catfish liver cells.
- To determine the receptor subtypes (alpha or beta) mediating these catecholamine effects.
- To explore the potential complexity of catecholamine signaling in catfish glycogenolysis.
Main Methods:
- Isolated catfish liver cells were treated with catecholamines (epinephrine, norepinephrine, isoproterenol, phenylephrine).
- The effects on intracellular cAMP levels were measured.
- Experiments were conducted with and without alpha- (phentolamine) and beta- (propranolol) receptor antagonists.
Main Results:
- All tested catecholamines elevated hepatocyte cAMP levels.
- The potency order was epinephrine = isoproterenol > norepinephrine > phenylephrine.
- Beta-receptor blockade with propranolol abolished the cAMP response, while alpha-receptor blockade with phentolamine had no effect.
Conclusions:
- The findings confirm that epinephrine and norepinephrine stimulate catfish liver cAMP production via beta-adrenergic receptors.
- Isoproterenol also increases cAMP through beta-receptors.
- The data suggest a more intricate mechanism than simple beta-receptor activation underlies the effects of certain catecholamines on catfish glycogenolysis, warranting further investigation.