Heat-induced changes in the rat parotid gland

Gland size, amylase activity, total proteins and DNA concentrations were measured in parotid gland during chronic heat exposure (34 degrees C). Subcellular fractionation was performed. Exposure to heat resulted in a decrease in gland size and in DNA concentration; amylase activity/100 mg tissue and amylase specific activity to protein concentration ratio increased. Subcellular fractions, except plasma membrane, decreased significantly. Thus, chronic heat exposure slows down the production of gland constituent proteins, whereas acinar function, e.g. the production and storage of exportable proteins, is not disturbed. The reduced gland size is apparently due to hypoplasia.