Immunoreactive calmodulin in cystic fibrosis kidneys.
BACKGROUND
Microscopic nephrocalcinosis has been detected at autopsy in 35 of 38 (92%) cystic fibrosis (CF) patients. A primary defect of calcium metabolism in the kidney has been postulated. Intracellular calcium and calmodulin (a calcium binding protein) have been shown to be increased in CF tissues.


OBJECTIVE
To determine whether CF kidneys obtained at autopsy contain normal amounts of calmodulin and whether the presence of immunoreactive calmodulin correlates with nephrocalcinosis.


METHODS
An immunoperoxidase method was used to stain kidneys obtained from six CF individuals aged three to 27.5 years (mean 15.75 +/- 10.2 years) and five individuals who died of chronic debilitating disease aged eight to 17 years (mean 13.6 +/- 3.9 years). Calcium staining was undertaken using the von Kossa (silver precipitation) and Alizarin red methods.


RESULTS
No quantifiable difference in immunoreactive calmodulin staining was demonstrated in autopsy renal specimens between six CF patients and five chronically diseased controls. Three of six CF patients aged 22.8 +/- four years and two of five chronically diseased controls aged eight to 16 years respectively had detectable immunoreactive calmodulin staining. Within the CF group the presence of microscopic nephrocalcinosis did not correlate with immunoreactive calmodulin staining.


CONCLUSIONS
This study does not support the premise that a calmodulin-dependent defect of intracellular calcium handling contributes to the microscopic nephrocalcinosis seen in CF.
Couper
R
R
Division of Gastroenterology, Hospital for Sick Children, University of Toronto, Ontario, Canada.
Bentur
L
L
Kilbourn
J P
JP
Wolf
P
P
D000293:Adolescent; D000328:Adult; D002147:Calmodulin / Q000032:analysis*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D009397:Nephrocalcinosis / Q000378:metabolism* / Q000473:pathology
D002147:Calmodulin