Abstract:The parotid and mandibular glands of the cotton rat were examined by light and transmission electron microscopy. Parotid gland: Acinar cells were serous in nature, and contained electron-dense granules. Intercalated duct cells contained electron-dense granules. Striated duct cells had small granules of moderate and high electron densities. Mandibular gland: Acinar cells were seromucous in nature, and contained granules of low and moderate electron densities. Intercalated duct cells contained granules of moderate and high electron densities. Striated ducts were comprised of two portions -a secretory portion and a striated portion without granules. The secretory portion had many electrondense granules. A sexual dimorphism was obserbed in these granules, which were smaller and fewer in females than in males.

umerous vasoactive substances are involved in the regulation of blood pressure, including reninangiotensin, atrial natriuretic peptide (ANP), endothelium-derived relaxing factor (EDRF), endothelin, and adrenomedullin. In 1986, it was established that EDRF is nitric oxide (NO), 1 which is secreted by vascular endothelial cells and maintains the homeostasis of vascular walls. The main effects of endothelim-derived NO in the circulatory system are relaxation of vascular smooth muscle and regulation of blood pressure. ANP was first isolated and characterized in 1984. 2 It is primarily synthesized and stored as granules in the cardiac atrium, and rapidly released into the blood stream during increased atrium Circulation Journal Vol.67, December 2003 load. The major effects of ANP are lowering of blood pressure, and water and sodium diuresis; and thus it is an important hormone in blood pressure regulation. The renin -angiotensin system also plays an important role in regulating blood pressure. Both angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blocker (ARB) are hypotensive agents that are involved in this system, and these agents are most useful drugs in the clinical setting because they have cardioprotective actions.Previous studies have reported on the administration of NO inhibitors, which increase blood pressure, and have dealt with the administration of ACEI and ARB. However, there is little information on the evaluation of ANP mRNA expression, ANP granules, ANP immunostaining, and changes in plasma ANP concentrations. Therefore, the present study examined the relationship between NO and ANP as vasoactive substances. Methods NO Inhibitor TreatmentNormotensive rats (Jcl: Wistar males, 30-40 g, 3 weeks old) were purchased from CLEA Japan (Kagoshima, Japan). Treatment was started at age 4 weeks and continued for 8 weeks. NO inhibitor was mixed into the food, and The aim of this study was to evaluate the effectiveness of an angiotensin-converting enzyne inhibitor (ACEI, quinapril) or angiotensin II receptor blocker (ARB, candesartan) on atrial natriuretic peptide (ANP) activity in rats with hypertension induced by nitric oxide (NO) inhibition. ACEI and ARB have a number of pharmacologic effects, including blood pressure reduction, myocardial preservation, and an unknown effect in the circulation. The changes in ANP in NO inhibitor-induced hypertensive rats were evaluated in order to elucidate the interaction between ANP and NO in the regulation of blood pressure. Thirty-six rats were divided into 4 groups and administered the experimental agents for 8 weeks: group Control was given regular food (n=9), group N G -nitro-L-arginine (L-NNA) was administered L-NNA (25mg·kg -1 ·day -1 , n=9), group ACEI was administered L-NNA and quinapril (10 mg·kg -1 ·day -1 , n=9), and group ARB was administered L-NNA and candesartan (10mg·kg -1 · day -1 , n=9 2) increased significantly. NO inhibitorinduced hypertension caused no changes in ANP concentrations. However, the ACEI and ARB had a direct effe...

The parotid glands of Tupaia glis were examined by light and transmission electron microscopy. The acinar cells were seromucous in nature, and contained many acidophilic granules with strong affinity for periodic acid-Schiff (PAS) and weak affinity for alcian blue (AB). These granules consisted of a fine granular matrix of moderate density in which a denser corpuscles or semilunar materials were present. Intercalated duct cells had a few fine vesicles, vacuoles and very few dense granules in the apical region. In occasional epithelial cells, acidophilic, PAS-positive and AB-negative bodies with moderate density were observed in the supranuclear region. The striated ducts consisted of columnar light and dark cells containing round or small ovoid granules of moderate density and did not show the granular duct as seen in the parotid glands of kobe mole and tenrec which are placed in the order insectivora.