Free Water Clearance Curves During Saline, Mannitol, Glucose and Urea Diuresis in the Rat
Article URL: http://jp.physoc.org/cgi/content/abstract/280/1/487
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, April 2008, she is Dean of Research and Graduate Programs at California Polytechnic State University - San Luis Obispo.
1. Free water clearances were measured during infusion of hypotonic saline, glucose, urea, and mannitol in Brattleboro rats. For each solute the free water clearances were plotted using either V or (CH2O + CNa) as the distal tubular delivery term.
2. In all cases the use of (CH2O + CNa) as distal delivery term yielded a steeper relationship than when V was used. There were no significant differences in the CH2O to V relationship when saline, glucose and mannitol was the solute infused. Urea, however, resulted in a curve with a slope significantly less than that for the other solutes.
3. When CH2O was plotted against (CH2O + CNa) there was still no significant difference between the slopes of the curves during saline or mannitol infusion. Use of this delivery term, however, resulted in a slope during glucose infusion which was significantly greater than that during saline or mannitol infusion. The slope for urea infusion remained lower than that for any other solute.
4. Regardless of the delivery term used, there was no significant difference in the slopes of the curves for awake Wistar and awake Brattleboro rats during mannitol infusion. This indicates that the awake rat is a suitable model for free water clearance studies.
5. The results indicate that NaCl and mannitol are both adequate for free water clearance and that (CH2O + CNa) is a better index of distal delivery than V.
Manuel Martinez-Maldonaldo and Susan C. Opava-Stitzer. "Free Water Clearance Curves During Saline, Mannitol, Glucose and Urea Diuresis in the Rat" Journal of Physiology 280 (1978): 487-498.
Available at: http://works.bepress.com/sopava/5