We examined into the secretory function of saliva stimulated by catecholamines in the rat submaxillary gland from viewpoint of changes in the cyclic-AMP levels. The following results were obtained. 1. In the intraperitoneal administration of adrenaline, noradrenaline or isoprenaline, the cyclic-AMP level increased in the rat submaxillary gland in comparison with the control level. 2. In the intraperitoneal administration of priscol or propranolol, the cyclic-AMP level was not affected. 3. In the pretreatment of priscol, alpha-blocking agent, the cyclic-AMP level induced by adrenaline or isoprenaline was not affected. Whereas, the level induced by noradrenaline was elevated by the pretreatment of priscol higher than that induced by noradrenaline alone. 4. In the pretreatment of propranolol, beta-blocking agent, the cyclic-AMP level induced by adrenaline, noradrenaline or isoprenaline was almost completely blocked.
1. A detailed composition of phospholipid has been examined in the rat submaxillary gland. It was recognized that there is phosphatidylcholine, phosphatidyl-ethanolamine (possibly containing phosphatidylserine) and sphingomyeline as a major constituent of phospholipids, that there is trace of lysophosphatidylcholine and unknown phospholipid. 2. The phospholipase A activity of unpurified tissue extract (fraction A) or purified tissue extract (fraction D), as the source of enzyme has been examined. The fraction A or fraction D hydrolysed phosphatidylcholine as a substrate, and liberate free fatty acid and formed lysophosphatidylcholine. From above results, it was established that phospholipase A activity is present in the rat submaxillary gland.