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Transepithelial water movement in response to carbamazepine, chlorpropamide and demeclocycline in toad urinary
1Department of Medicine, School of Postgraduate Medicine and Biological Sciences, University of Keele, Hartshill, Stoke on Trent.
Abstract:
1. Osmotic water movement across toad isolated hemibladders was measured by a gravimetric method. 2. The influence of carbamazepine, chlorpropamide and demeclocycline on the antidiuretic hormone (ADH)-induced water flow rate was examined. 3. No antidiuretic activity due to carbamazepine alone was observed but a slight inhibition due to ADH-induced water flow was observed in the presence of carbamazepine over a selected dose-range. This was unexpected and is inconsistent with data from in vivo studies in man. 4. Chlorpropamide potentiated ADH-induced water flow, in keeping with the hypothesis that chlorpropamide sensitizes the renal tubules to ADH-induced water flow. 5. Demeclocycline inhibited ADH-induced water flow. The mechanism of action remains unclear.