title: [Relaxant effects of protamine sulfate on isolated renal arteries of normotensive and hypertensive rats].
abstract: BACKGROUND
  Protamine sulfate is found to have endothelium-dependent relaxing effect on isolated blood vessels. The aim of our experiments was to study relaxant effects of protamine sulfate on isolated renal arteries of both normotensive and hypertensive rats.
  
  
  METHODS
  Experiments were performed on renal arteries, isolated from male, Wistar, spontaneously hypertensive rats (250-300 g). The adhering perivascular tissue was carefully removed from arteries which were then cut into 3-5 mm ring segments, incubated 30 min in water bath in Krebs-Ringer bicarbonate solution at 36 degrees C, and gassed with 95% O2 and 5% CO2. Each was gradually stretched to optimal tension (2 g) and isometric transducer registered mechanical contractions. Contractions of isolated blood vessels were caused by phenylephrine (10(-6) mol) and functional integrity of the endothelium was confirmed by acetylcholine (10(-5) mol) and histopathological examination.
  
  
  CONCLUSIONS
  Preparations were analyzed using a microscope to distinguish differences between blood vessels of normotensive and hypertensive rats. The reason for this effect of protamine is probably its stimulating effect on nitrogen-monoxide release, which might be the main reason for systemic hypotension that occurs during protamine infusion. It occurs due to activation of endothelial NO-synthesis. Our results show a better relaxant effect of protamine with normotensive, comparing to hypertensive rats, regarding to better preservation of endothelium with normotensive animals.
  
  
  CONCLUSIONS
  The relaxant effect of protamine occurs due to NO release with conductance artery, which is not the case with microvessels, where this effect occurs due to endothelium-derived hyperpolarizing factor release.
authors.affiliation: zoranaor@imi.bg.ac.yu
authors.forename: Zorana
authors.initials: Z
authors.lastname: Oresscanin
authors.forename: Slobodan R
authors.initials: SR
authors.lastname: Milovanović
authors.forename: Mihajlo
authors.initials: M
authors.lastname: Spasić
mesh_terms: D000818:Animals; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D011479:Protamines / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D012077:Renal Artery / Q000187:drug effects* / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D011479:Protamines