Protein Breakdown in the Isoproterenol-induced Hypertrophy of Rat Submandibular Glands

Abstract

The rate of protein breakdown in the ISO-induced hypertrophy of rat submandibular glands was investigated by measuring the release of free tyrosine from cell protein in the gland tissues and further, the effect of aprotinin, protease inhibitor on the protein breakdown was also investigated. 1. The decreasing tendency in the protein breakdown was observed in the gland tissues removed from rats on the 3rd day and the 5th of ISO-injection, although not significant. 2. The significantly reduced protein breakdown was observed in the gland tissues removed from rats on the 7th day and the 10th day of ISO-injection. 3. The protein breakdown was significantly reduced by aprotinin in the normally growing gland tissues, but not in hypertrophied gland tissues removed from rats on the 7th day of ISO-injection. These findings suggest that the ISO-induced hypertrophy of submandibular glands is implicated in the decreased protein breakdown and in the reduction of protein catabolism by the decreased serine protease activity in the hypertrophied glands