Studies on dog saliva. IV. The effect of carbohydrate diet on the activity of some hydrolytic enzymes.

Abstract

Six mongrel dogs were reared after weaning on a daily diet composed of (1) raw bovine meat (35 %) containing sucrose (65 %), (2) bovine milk with 10 % sucrose, and (3) water. Five control dogs were kept on a similar diet without sucrose. the experiment was carried out for 260 days. No differences between the groups were observed when comparing the rate of growth, eruption pattern of deciduous and permanent teeth and blood sugar concentration. Hydrolases acting on ester and peptide bonds and glycosyl compounds were studied in the supernatant and sediment fraction of centrifuged dog saliva using altogether 41 different substrates. When comparing the values obtained to those of man the following deviations were observed: the sugar diet did not induce the appearance of salivary α-amylase (EC 3.2.1.1.), proline iminopeptidase (EC 3.4.1.4.) nor acid phosphatase (EC 3.1.3.2.) activity. With a few exceptions, the total hydrolytic enzyme activity in the oral cavity seemed to be constant. However, a fourfold increase was noticed in the hydrolysis of 6-hromo-2-naphthyl-α-D-glucoside, possibly representing a-glucosidase (EC 3.2.1.20) activity. the salivary protein concentration increased in the sugar group whereas it decreased in the meat group. No initiation of dental caries was obtained in any of the dogs. These observations were though to support the view that in the oral enzyme spectrum differences due to the diet and interspecies variations do occur.