Enhanced responses to L-arginine in aortic rings from rats with angiotensin-dependent hypertension.
We contrasted, in normotensive and hypertensive rats, the effect of L-arginine on isometric tension of phenylephrine-contracted rings of aorta bathed in Krebs' bicarbonate buffer on cyclic guanosine monophosphate content of aortic rings and on blood pressure. L-Arginine had no effect on isometric tension or cyclic guanosine monophosphate content of aortic rings from normotensive controls. Conversely, L-arginine (10(-5)-10(-3) mol/l) induced concentration-dependent relaxation of unrubbed and rubbed rings of thoracic and abdominal aorta and, as well, L-arginine (10(-3) mol/l) increased cyclic guanosine monophosphate in unrubbed and rubbed rings of thoracic aorta taken from hypertensive rats 7 to 14 days after aortic coarctation. Similar relaxations to L-arginine were seen in rings of thoracic and abdominal aorta from rats made hypertensive by infusion of angiotensin II for 7 to 8 days but not in rings of thoracic aorta from rats with aortic coarctation-induced hypertension of 28 to 42 days. Relaxant responses to L-arginine in rings of thoracic aorta from hypertensive rats 7 to 14 days after aortic coarctation were unaffected by pretreatment of rings with dexamethasone (10(-7) mol/l) or L-arginine (10(-4) mol/l) but were blunted by NG-nitro-L-arginine methylester (3 x 10(-4) mol/l) or methylene blue (10(-5) mol/l). Our results suggest that the vasorelaxant effects of L-arginine in aortic rings from hypertensive rats 7 to 14 days after aortic coarctation and 7 to 8 days after commencing angiotensin II infusion are mediated by nitric oxide.(ABSTRACT TRUNCATED AT 250 WORDS)
Pucci
M L
ML
Department of Pharmacology, New York Medical College, Valhalla, USA.
Dick
L B
LB
Miller
K B
KB
Smith
C J
CJ
Nasjletti
A
A
D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000503:physiopathology; D001017:Aortic Coarctation / Q000503:physiopathology; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000804:Angiotensin II; D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester