Differences between cystic fibrosis and normal saliva alpha-amylase as a function of age and sex.

Alpha-amylase activity and protein concentration of cystic fibrosis (CF), obligate heterozygote (H), 
and normal (N) saliva have been evaluated with respect to genotype, 
age, sex and clinical status. "Factors" present in CF saliva had 
no detectable effect on salivary amylase activity under reaction conditions optimized 
for both competitive and noncompetitive inhibition. Tris [tris-(hydoxy-methyl)aminomethane] inhibited amylase activity 
with a Ki = 59 plus or minus 10 mM, but 
CF "factors" had no detectable effect on either substrate or Tris 
binding to alpha-amylase. Alpha-amylase concentrationand protein content of CF saliva had 
bimodal distributions. Thirty-six percent of the CF patients were found to 
be amylase hypersecretors, with amylase concentration 3 or more SD above 
the N mean. Amylase hypersecretion was marginally correlated with both genetic 
factors (with parent values, P = 0.075) and clinical status (with 
Scwachman scores, P = 0.068). All the hypersecretors were in the 
14-24 year age group. Amylase concentration for this age was significant 
higher in CF samples (mean plus or minus SD), 82 plus 
or minus 37 starch units/ml (n = 12), than in N 
samples, 33 plus or minus 17 starch unites/ml (n = 13), 
as measured by the Student t-test (P < 0.001). Salivary protein 
content of 14- to 24-year-old CF males was elevated compared to 
all other groups [1.57 plus or minus 0.76 (n = 5) 
vs. 0.63 plus or minus 0.47 (n = 20); Student t-test, 
P < 0.005]. Mean specific activity of male saliva dropped sharply 
as age increased from 10-15 years, from over 200 to less 
than 75 starch units/mg protein. Mean normal female specific activity values 
were essentially constant [97 plus or minus 50 (n = 18) 
starch units/mg protein] from 5-30 years of age. CF male specific 
activity values decreased similarly to the N male values from preadolescence 
to adolescence, but the mean CF female values peaked later, at 
17 years, with a maximum of 171 plus or minus 58 
(n = 4). This is significantly higher than all the other 
groups in the 16- to 20-year age range: 63 plus or 
minus 30 (n = 9), P < 0.005. These data emphasize 
the need for age- and sex-matched controls in all studies of 
salivary composition. We were unable to detect any effect of a 
salivary CF factor on the enzymatic activity of alpha-amylase. Hypersecretion of 
salivary alpha-amylase was observed in 36% of CF patients. This may 
reflect alterations in secretory function basic to CF, or be secondary 
to the disease process and result from decreased secretion from the 
mucous salivary glands or deterioration of pancreatic function. 