AJP - Renal Physiology, Vol 250, Issue 5 845-F849, Copyright © 1986 by American Physiological Society
Time-dependent attenuation of water flow in antidiuretic hormone-treated toad bladder
W. A. Kachadorian, J. Muller and S. J. Ellis
Toad urinary bladders were subjected to sequential 30-min stimulation with
antidiuretic hormone (ADH) followed by 30-min hormone washout over 4 h in
the absence of a transmural osmotic gradient. Immediately thereafter,
during test stimulation with hormone in the presence of a transmural
gradient, transbladder water flow was profoundly inhibited, but
intra(luminal)membrane particle aggregates, presumed markers of luminal
membrane water permeability, were as numerous as in fully responsive
controls. The protocol followed was designed to eliminate any distorting
effect of prior water flow on cytoplasmic organization and to equalize, for
both experimental and control tissues, the time of aggregate presence in
the luminal membrane during final test stimulation. On the assumption that
cytoplasmically stored and/or newly synthesized aggregates would be
unaffected by the protocol followed, these observations appear to be
consistent with the view that bladder refractoriness to prolonged ADH
treatment may involve regulation of tissue water permeability at a
resistance distal to the luminal membrane.
