Inhibitory effects of 1-iodo-3-aminomethyl-5,6,7,8-tetrahydro-2-naphthol (ONO-3122) and prostaglandin H2 on vasopressin-induced osmotic water flow in toad bladder

1982 ◽  
Vol 38 (7) ◽  
pp. 828-829
Author(s):  
F. Marumo
Keyword(s):  
Water Flow ◽  
Toad Bladder ◽  
Inhibitory Effects ◽  
Osmotic Water ◽  
Osmotic Water Flow

Modulation of vasopressin action by reducing agents in Bufo marinus

1982 ◽  
Vol 243 (1) ◽  
pp. C52-C61 ◽  
Author(s):  
D. E. Butkus ◽  
J. H. Schwartz
Keyword(s):  
Adenylate Cyclase ◽  
Water Flow ◽  
Water Permeability ◽  
Regulatory Protein ◽  
Inhibitory Effect ◽  
Bufo Marinus ◽  
Inhibitory Effects ◽  
Thiol Compounds ◽  
Osmotic Water ◽  
Osmotic Water Flow

The effects of the reducing agent dithiothreitol (DTT) on vasopressin (AVP)-stimulated osmotic water flow and adenylate cyclase activity were studied in the urinary bladder of Bufo marinus. DTT produced concentration-dependent inhibition of the hydroosmotic water permeability response to 10 mU/ml AVP and 10 mM theophylline but did not inhibit the response to 10 mM adenosine 3',5'-cyclic monophosphate (cAMP). The inhibitory effects of DTT on AVP responsiveness were partially reversed by washing in DTT-free Ringer solution or by addition of oxidizing agents such as dehydroascorbic acid (DHA) or H2O2. The inhibitory effects of DTT were completely reversed by washing in DTT-free Ringer plus addition of DHA. In addition, the inhibitory effects of DTT on AVP-induced osmotic water flow were partially reversed by the GTP analogue 5'-guanylyl imidodiphosphate [Gpp(NH)p]. DTT also inhibited the adenylate cyclase response to AVP but did not alter the response to AVP plus Gpp(NH)p or the response to NaF. These observations suggest that the inhibitory effect of thiol compounds on AVP responsiveness may be modulated through alterations of a redox system distal to the hormone receptor but proximal to the catalytic subunit of adenylate cyclase. Inasmuch as Gpp(NH)p partially reversed the inhibitory effects of DTT on AVP-stimulated osmotic water permeability and prevented the inhibitory effect of DTT on AVP-stimulated adenylate cyclase, an effect on either GTPase or binding of GTP to the regulatory protein of adenylate cyclase is suggested by these observations.

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