NITRIC-OXIDE SYNTHASE ACTIVITIES IN MAMMALIAN PAROTID AND SUBMANDIBULAR SALIVARY-GLANDS

Nitric oxide is important as a physiological messenger molecule in var ious organs and cells., It is synthesized from the amino acid L-argini ne by nitric oxide synthase. Here, the specific activities of nitric o xide synthase in the cytosolic fractions of rabbit, bovine, mice, rat, and guinea-pig parotid and submandibular glands were compared. Marked specific activities were detected in the rabbit and bovine parotid an d submandibular glands and in the parotid of mice. The activity in rab bit parotid was highest and was similar to that in rabbit brain. The s ignificant activities in the salivary glands were completely blocked i n the absence of Ca2+ or the presence of a calmodulin inhibitor. These findings suggest that the rabbit parotid glands are useful for studyi ng the regulation of nitric oxide generation by Ca2+/cal-modulin-depen dent nitric oxide synthase in salivary glands. (C) 1997 Elsevier Scien ce Ltd.