Author Posting. © New York Academy of Sciences 1982. This is the author's version of the work. It is posted here by permission of the New York Academy of Sciences for personal use, not for redistribution. The definitive version was published in Annals of the New York Academy of Science, Volume 394, October 1, 1982, pages 219-230. http://dx.doi.org/10.1111/j.1749-6632.1982.tb37430.x
NOTE: At the time of publication, the author Susan C. Opava-Stitzer was affiliated with the University of Puerto Rico School of Medicine - San Juan, Puerto Rico. Currently, May 2008, she is Dean of Research and Graduate Programs at California Polytechnic State University - San Luis Obispo.
A state of chronic dehydration with reduced plasma volume, decreased blood pressure, and increased plasma renin activity (PRA) has been demonstrated in rats with hereditary hypothalamic diabetes insipidus (DI) rats. In this situation decreased renal perfusion and glomerular filtration rate might result in sodium retention. On the other hand, the DI rat also suffers from mineralocorticoid deficiency which might result in salt wasting. In addition it has recently been shown that in contrast to normal rats, there are no differences between superficial cortical and juxtamedullary nephrons of the DI rat with respect to single nephron filtration rate, glomerular volume, and proximal tubular length. This lack of internephron heterogeneity might also affect renal sodium handling in the DI rat. It thus seems of particular interest to evaluate the natriuretic response of DI rats to volume expansion.
In the present study, the natriuetic responses of DI and normal Long-Evans rats to acute and chronic volume expansion were compared. Other factors involved in sodium handling, namely mineralocortoids and renal (Na+ + K+) - ATPase activity, were also studied.