Differential contribution of nitric oxide and prostaglandin to regional hemodynamics in normotensive and hypertensive rats

• Published in: Japanese Journal of Pharmacology 1993, Vol.61 (suppl.1), p.235-235
• Main Authors: Okita, Minori, Shinyama, Hiroshi, Kawamura, Toru, Uchida, Takeshi, Watanabe, Masahiro
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-5198
• DOI: 10.1016/S0021-5198(19)51806-6

Endothelium-derived relaxing factors such as nitric oxide (NO) and prostaglandin I_2 (PGI_2 ) are thought to play an important role in regulation of regional hemodynamics. The purpose of the present study was 1) to elucidate the role of NO and PG in regulation of blood flow of major cardiovascular organs and 2) to compare their contribution between normotensive and hypertensive animals. Organ blood flow was measured by the radioactive microsphere technique in conscious normotensive Wistar (WR) as well as in stroke-prone SHR (SHRSP) rats after administration of 1-nitro-arginine (LNA, 10 mg/kg iv), an inhibitor of NO synthase, or indomethacin (IND, 10 mg/kg sc). LNA caused markod rises in total peripheral resistance (TPR) and vascular resistance (VR) in all organs measured (i.e., brain, heart, kidney and adrenal gland) in SHRSP, whereas only slight change was observed in WR receiving LNA, suggesting that the release of NO from endothelium may be rather enhanced in severe hypertension. In contrast, IND predominantly increased cerebral VR without significant changes in TPR in both strains. These results suggest that NO participates in the regulation of regional blood flow without organ specificity. In contrast. PG (possibly PGI_2 ) might preferentially contribute for the cerebral circulation.