Iodine metabolism and peroxidase activity in salivary glands

The coincidence between iodine-concentrating ability and peroxidase activity in salivary glands has been studied. In 19 of 24 types of salivary glands examined the two activities either occurred together or were both absent. 3 of the glands gave inconclusive data.

The iodine metabolism was studied in the three main salivary glands of six different animal species. Paper chromatography of salivary gland homogenates revealed that 131I- injected intraperitoneally before salivary gland extirpation is only metabolized as iodide, whether or not the gland is capable of concentrating iodide or contains a peroxidase.

The findings are discussed with special reference to some possible functions for peroxidase in salivary gland metabolism.

The activities were not correlated either to the serous or to the mucous type of gland.

The electrical response of isolated salivary glands during stimulation with 5-hydroxytryptamine and cyclic AMP

Rate of fluid secretion by the salivary glands of the blowfly Calliphora is regulated by 5-hydroxytryptamine (5-HT) working in conjunction with cyclic AMP. Although cyclic AMP can exactly mimic the acceleration of fluid secretion produced by 5-HT, the underlying electrical events are completely different. Transepithelial potentials were measured by a liquid paraffin-gap technique which permits continuous potential recordings during rapid changes of the bathing medium. The potential of the lumen of unstimulated glands is + 5 mV with respect to the bathing medium but becomes — 10 to 20 mV after applying 5-HT. After stimulation with cyclic AMP, however, the luminal potential becomes more positive (+ 30 to 40 mV). A similar effect is obtained with theophylline or when glands are treated with 5-HT in the presence of an impermeant anion such as isethionate. These observations suggest that in addition to stimulating the synthesis of cyclic AMP, 5-HT may also act directly to increase anion movement. Cyclic AMP appears to stimulate cation transport, which explains the increase in positive potential obtained when this compound (or theophylline) is applied in the absence of 5-HT.

Localization and onset of amylase activity in mouse salivary glands determined by a substrate film method

A starch substrate film technique was used to determine the localization and onset of amylase activity in the major salivary glands of mice. The earliest activity occurred in the parotid gland of males and females at 8 days of age. The intensity of the reaction rapidly increased so that by day 16 the entire parotid gland was amylase-positive. The submandibular gland exhibited the sexual dimorphism that has been characterized for the adult gland. Amylase activity was observed in the male at 24 days of age, shortly after the first morphologic differences between the submandibular glands of males and females became apparent. The female showed positive results at 36 days of age. Amylase activity in the submandibular glands was localized to the convoluted tubules. As the gland developed, the amylase activity increased in correlation with the increasing concentration of these tubules. The sublingual gland was always amylase-negative.