Nitric oxide does not contribute to sodium retention and peripheral vasodilation induced by partial portal vein ligation in rats.
The role of nitric oxide (NO) synthesis in the peripheral vasodilation and sodium retention that occurs after partial portal vein ligation (PVL) was investigated. Hemodynamic studies in PVL rats with sodium retention and in sham-operated controls were conducted on the day when PVL rats developed transient and maximal sodium retention. Measurements were obtained before and during two consecutive periods after NO synthesis inhibition with NG-monomethyl-L-arginine (L-NMMA). Under baseline conditions, PVL rats with sodium retention were hypotensive, with equivalent decreases in total peripheral resistance and glomerular filtration rate in comparison to the control group. After L-NMMA, peripheral resistance and arterial pressure increased by similar extent in both groups. As compared with controls, PVL rats with sodium retention remained hypotensive and vasodilated. Furthermore, L-NMMA-induced natriuresis was attenuated in the PVL group. Additionally, serum and urinary levels of nitrate and nitrite did not vary before surgery and at the time of sodium retention. These results suggest that in PVL rats (1) vasodilation is not NO mediated; (2) vasodilation is not a sufficient explanation for sodium retention, and (3) a sodium-retaining factor acting on the renal tubules is responsible for sodium retention.
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D008026:Ligation; D008297:Male; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D011169:Portal Vein / Q000503:physiopathology* / Q000601:surgery; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D019323:omega-N-Methylarginine
D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D012964:Sodium