Comparison of proximal tubule fluid-to-plasma ultrafiltrate chloride ratio in rats and dogs.
Previous studies in rats have demonstrated that the concentration of chloride in proximal tubule fluid is greater than that in plasma. The gradient reaches a free-flow steady-state level in the early proximal tubule and is maintained throughout the accessible proximal tubule. On the other hand, studies in dogs are in conflict regarding either the existence of a gradient or the development of a free-flow steady-state level. Since a species difference of tubule fluid to plasma chloride (TF/PC1) may exist, the present study was done to systematically compare the tubule fluid to ultrafiltrate chloride ratio (TF/UFC1) in hydropenic rats and dogs during normal acid-base balance. Chloride was analyzed by microelectrometric titration. In the rat the TFC1 and UFC1 concentrations were 139 +/- 1.4 and 120 +/- 1.2 meq/1, respectively. In the dog the TFC1 and UFC1 concentrations were 138 +/- 1.3 and 121 +/- 1.5 meq/1, respectively. Thus, there was no significant difference in the TF/UFC1 ratio between the rat (1.17 +/- 0.02) and the dog (1.14 +/- 0.01). Furthermore, regression analysis indicates that there is no correlation between TF/UFC1 and TF/PIn in either the rat or dog, which suggests that the gradient originates early in the proximal tubule and is maintained throughout the accessible proximal tubule in both species.
D000818:Animals; D002712:Chlorides / Q000097:blood / Q000378:metabolism*; D004285:Dogs; D005260:Female; D005919:Glomerular Filtration Rate; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D051381:Rats; D013045:Species Specificity
D002712:Chlorides