Tetracycline-induced inhibition of Na+ transport in the toad urinary bladder.
The effects of three tetracyclines, demethylchlortetracycline (DMC), minocycline (MNC), and oxytetracycline (OTC), on Na+ transport (measured as short-circuit current) were examined in toad urinary bladders mounted in modified Ussing chambers. During a 1-h incubation period serosal DMC (but not MNC or OTC) inhibited basal Na+ transport, whereas MNC (but not DMC or OTC) inhibited ADH-stimulated Na+ transport. MNC also inhibited cyclic AMP-stimulated Na+ transport. During longer incubation periods all three drugs inhibited basal Na+ transport. The DMC-induced inhibition of basal Na+ transport and the MNC-induced inhibition of ADH-stimulated Na+ transport were paralleled by an inhibition of the active conductance of the bladders. Thus, although all three drugs inhibit basal Na+ transport, only MNC inhibits ADH-stimulated Na+ transport. This effect does not correlate with the known effects of the tetracyclines on ADH-stimulated water flow or with drug-protein binding, and may be related to the greater lipid solubility of MNC.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002024:Bufo marinus; D003707:Demeclocycline / Q000494:pharmacology; D005260:Female; D008911:Minocycline / Q000494:pharmacology; D010118:Oxytetracycline / Q000494:pharmacology; D012044:Regression Analysis; D012964:Sodium / Q000378:metabolism*; D013754:Tetracyclines / Q000494:pharmacology*; D013997:Time Factors; D001743:Urinary Bladder / Q000378:metabolism*; D014667:Vasopressins / Q000494:pharmacology
D013754:Tetracyclines; D014667:Vasopressins; D003707:Demeclocycline; D012964:Sodium; D008911:Minocycline; D010118:Oxytetracycline