AJP - Cell Physiology, Vol 249, Issue 1 84-C88, Copyright © 1985 by American Physiological Society
Persistent stimulation of adenylate cyclase and urea transport by an AVP photolabel
P. Eggena, C. L. Ma, F. Fahrenholz and I. L. Schwartz
The effects of a photoaffinity label for arginine vasopressin receptors,
[Phe2, Phe(p-N3)3]AVP (N3-AVP), on urea permeability and adenylate cyclase
activity have been investigated in the toad urinary bladder. This compound,
when activated by ultraviolet light, induced a maximal and persistent
increase in the urea permeability of the intact bladder and a persistent
increase in the adenylate cyclase activity of toad bladder epithelial cell
homogenates. Covalent attachment of the analogue to target tissue during
photolysis was equivalent at 4 and 20 degrees C. Bladders exposed to N3-AVP
in the presence of AVP during photolysis were substantially less permeable
to urea than controls that had been exposed to N3-AVP alone. These findings
constitute further evidence in support of our previous suggestion that
N3-AVP binds covalently to AVP receptors and, in addition, demonstrates
that N3-AVP evokes a persistent increase in adenylate cyclase activity
which, in turn, triggers a persistent increase in bladder permeability to
urea.
