The Influence of Anaesthetics on the Increase in the Water Permeability of the Toad Bladder Induced by Vasopressin

Abstract

1Single lobes of the bladder of Bufo marinus were isolated and filled with, and suspended in, oxygenated Ringer solution. The fluid in contact with the outside (serosa) of the lobes had a total osmolarity of 225 m-osmol/litre, and that bathing the inside (mucosa) of 45 m-osmol/ litre. 2 Osmotic water flow from mucosa to serosa was measured by weighing the lobes every 30 minutes. It was negligible unless vasopressin was added to the serosal bath. Standard concentrations of either 1.25 or 6.25 mu/ml were used to render the bladder lobes permeable to water.3 The presence in the serosal medium of pentobarbitone or thiopentone in concentrations ranging from 0.25 to 2.5 mM, or of chloralose in concentrations ranging from 0.65 to 6.5 mM, diminished the increase in water permeability induced by vasopressin. 4 The three anaesthetics exerted similar inhibitory effects on the action of vasopressin from the serosal and from the mucosal surface of the bladder. 5 In the presence of a constant high concentration of anaesthetic, increasing the concentration of vasopressin over three orders of magnitude led to stepwise increases of osmotic water flow out of the lobes, although at every dose level the effect of vasopressin was depressed by the anaesthetic. However, it was not completely abolished even if the concentration of vasopressin was close to threshold. 6 The increase in water permeability of the bladder induced by 3',5'-adenosine monophosphate (cyclic AMP) was also depressed by the three anaesthetics. 7 Possible explanations of the findings are discussed.

Selective inhibition of osmotic water flow by general anesthetics to toad urinary bladder.

“…In contrast, neither methohexital nor methoxyflurane depressed cyclic nucleotide-stimulated water flow, suggesting that the anesthetics alter intracellular cAMP levels and adenylate cyclase activity, rather than modifying cAMPs' effect at the luminal membrane. Grey and Ullmann have recently demonstrated inhibition of both vasopressin and cAMP-stimulated water flow by the barbiturate anesthetics pentobarbital and thiopental (18). Their cAMP studies were, however, performed at very high anesthetic concentrations (2.5-6.5 mM) and recovery of permeability after removal of anesthetic was incomplete, so that the effects they observed may well have been more widespread than in our study because of the higher anesthetic concentrations used.…”

Metrizamide in Experimental Urography. VI. Effects of Renal Contrast Media on Urinary Solutes

“…A higher value of TCH,O after infusion of NaCl than of mannitol was also found by GOLDBERG et al (1965). Both these findings and the acceptable fit of all the data in the present study to the relation between TCH,O and Cosm, indicating that TCII,O is affected in the same way by the three contrast media, give further support to the theory that sodium transport in the ascending limb of Henle, necessary for establishing an osmotic concentrating gradient, is dependent on chloride as the specific accompanying anion ( WALLIN et al 1973;IMAI & KOKKO 1974) and not on impermeable anions, as for instance contrast agents.…”