Protein Breakdown in Submandibular Glands Rendered Hypertrophic by Amputation of Lower Incisor Teeth in Rats

Abstract

Protein breakdown in submandibular glands rendered hypertrophic by amputation of the lower incisor teeth in rats was investigated. Reduced protein break-down was observed in the hypertrophic gland tissues, and was found to be inhibited by 20 mM ε-amino-n-caproic acid, an inhibitor of serine protease, and 50 μM leupeptin, an inhibitor of trypsin, plasmin, papain and cathepsin B, but not by 2 mM PMSF (phenylmethylsulfonyl fluoride), an inhibitor of serine protease, 10 μM pepstatin, an inhibitor of cathepsin D and 20 μM antipain, an inhibitor of cathepsin A and B. These results suggest that some serine proteases and leupeptin-sensitive proteases (presumably cathepsin B) participate in protein breakdown in hypertrophic gland tissues, and that hypertrophy of the submandibular glands is closely related to the reduced protein breakdown in these tissues.