Urolithiasis was induced in an experimental group of Single Comb White Leghorn pullets by feeding them layer ration and exposing them to nephrotrophic Gray strain infectious bronchitis virus (IBV). Gray strain IBV was recovered from kidney and cloacal swabs for up to 26 days after exposure to the virus. Control pullets fed pullet grower ration and not exposed to Gray strain IBV did not develop urolithiasis. The experimental design did not allow differentiation between the roles of layer ration and IBV in triggering urolithiasis. Urolithiasis was associated with asymmetry in left vs. right kidney weight comparisons for individual pullets. Pullets from the urolithiasis group had 43,800 +/- 4,500 glomeruli/gram kidney weight, whereas control pullets had 68,770 +/- 3,500 glomeruli/gram kidney weight. This difference was significant (P less than .01). Total kidney weights did not differ significantly when the experimental and control pullets were compared. Comparisons of glomeruli size distributions indicated that the number of intermediate sized glomeruli (.15 to .22 mm in circumference) was significantly reduced in pullets from the urolithiasis treatment group. These observations indicate that a significant reduction in nephron number can be masked by compensatory hypertrophy of the remaining kidney tissue in pullets with urolithiasis.
Nephrons in the avian kidney have an extremely heterogeneous size distribution. The shortest nephrons have very small glomeruli, and the larger nephrons have very large glomeruli. Physiological, nutritional, and disease factors may be correlated with the functioning of different sized nephrons. The present study was conducted to compare two techniques for measuring glomerular size distributions. A postmortem India ink infusion technique gave results that were highly comparable to an in vivo alcian blue infusion technique. Single Comb White Leghorn pullets were found to have approximately 270,000 glomeruli per kidney; glomerular circumferences and diameters ranged between .07 to .42 mm and .02 to.14 mm, respectively. A unimodal size distribution was found, with most glomeruli falling within the circumference range of .15 to .26 mm. The alcian blue technique should provide a quantitative in vivo method for evaluating selective tubular damage or physiological glomerular intermittency.
Exogenous parathyroid hormone (bovine 1-84 PTH) was infused unilaterally into the renal portal system or unilaterally into the renal arterial system of domestic fowl. Endogenous PTH was secreted unilaterally into the renal portal system by parathyroid tissue transplanted to the leg muscle. None of the experimental protocols caused significant unilateral phosphaturia, although unilaterally infused kidneys were shown to have received significantly more PTH than the contralateral kidneys. The transplanted parathyroid tissue was a major source of endogenous PTH, as was indicated by the development of significant hypocalcemia following surgical removal of the transplant. Unilateral PTH infusion did cause a significant unilateral increase in sodium excretion and significant bilateral phosphaturia. These results demonstrate that the phosphaturic and natriuretic responses to PTH can be dissociated in clearance experiments.
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