Renal response of roosters with diabetes insipidus to infusions of
arginine vasotocin.
Brummermann, M., and E. J. Braun.
Department of Physiology, University of Arizona, Tucson, AZ
85724
APStracts 2:0044R, 1995.
In a strain of white Leghorn chicken with symptoms of hereditary
diabetes insipidus (DI) and with elevated circulating levels of
antidiuretic hormone (AVT), we investigated whether the defect is
based on non-functional endogenous AVT or on a diminished renal
response to AVT. DI chickens responded to hypoosmotic infusions with
a higher urine flow and lower glomerular filtration rate (GFR) than
healthy control birds. Urine osmolality, fractional excretion and
clearance of sodium were lower in DI birds, while potassium values
were similar in both groups. Hence, the DI birds' high urine flow
rate was predominantly based on a water diuresis. When infused with
AVT the GFR and the urine flow of the control birds decreased and
urine osmolality increased, showing both glomerular and tubular
effects of AVT. During AVT infusion, the GFR of DI birds increased,
urine flow decreased only moderately, and urine osmolality was half
that of the control birds. In control birds the clearance of sodium
was unchanged, while that of potassium decreased. In DI birds, which
experienced a strong natriuresis, the clearance of both sodium and
potassium increased. These data suggest that the sensitivity of the
DI birds to AVT is reduced at the tubular level. The AVT-induced
increase in GFR may be related to vascular effects of high AVT doses,
added to the already high basal AVT level of the DI birds, in
combination with an imbalance in the function of V1 and V2 receptor
-subtypes in these chickens.
Received 29 March 1994; accepted in final form 7 February 1995.
APS Manuscript Number R157-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.