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Comparative effects of catecholamines, angiotensin II and antidiuretic hormone on chloride transport in toad skin
Abstract:
In this work we present data which show stimulation of Cl- transport in the isolated toad skin by four agonists: L-isoproterenol, L-adrenalin, angiotensin II and ADH. This response was demonstrated by raising mucosal amiloride concentration to block the sodium transport in the skin. With transepithelial sodium influx almost completely inhibited, it was likely that the response reflected transport events in the glands. Inhibition of the bioelectric parameters by removing chloride from the serosal bathing medium in the amiloride-inhibited preparation eliminated the response to all four agents, indicating that these responses are chloride dependent. The similarity of the bioelectric responses of the amiloride-treated preparation to db cAMP and to the four agents tested in this work add further evidence that this second messenger may account largely for the Cl- transport mechanism in the toad skin glands by increasing the apical membrane permeability to Cl-.
Insights
This study reveals that four agonists stimulate chloride transport in toad skin glands, likely mediated by cyclic AMP (cAMP). This chloride transport mechanism is crucial for gland function.
Area of Science:
- Physiology
- Membrane Transport
- Endocrinology
Background:
- Toad skin is a model for studying epithelial transport.
- Hormonal regulation of ion transport in skin glands is not fully understood.
Purpose of the Study:
- To investigate the role of specific agonists in stimulating chloride transport in isolated toad skin glands.
- To elucidate the underlying signaling pathways involved in this chloride transport.
Main Methods:
- Isolated toad skin preparations were used.
- Sodium transport was inhibited using amiloride.
- Chloride-dependent bioelectric parameters were measured.
- Responses to L-isoproterenol, L-adrenalin, angiotensin II, and ADH were assessed.
Main Results:
- Four agonists (L-isoproterenol, L-adrenalin, angiotensin II, ADH) stimulated chloride transport in toad skin glands.
- The observed responses were chloride-dependent.
- The effects mimicked those of cyclic AMP (cAMP), suggesting its involvement.
Conclusions:
- The data suggest that cAMP mediates chloride transport in toad skin glands.
- Increased apical membrane permeability to chloride is a likely mechanism.
- This finding enhances understanding of hormonal regulation in epithelial tissues.