Effects of NG-nitro-L-arginine on the blood pressure of spontaneously hypertensive rats with different degrees of hypertension.
The effects of NG-nitro-L-arginine (L-NNA) on blood pressure of various strains of spontaneously hypertensive rats were studied. Blood pressure of the rats was higher in the order of WKY, SHR, SHRSP, M-SHRSP. L-NNA caused an elevation of the blood pressure, which was greatest in SHR and smallest in WKY and M-SHRSP. Endothelium-dependent relaxation of aortae by acetylcholine was greatest in preparations from WKY and it decreased as the blood pressure of rats increased. Phenylephrine (higher than 10(-6) mg/kg) caused an elevation of the blood pressure, which was greatest in SHR and smallest in M-SHRSP. It was suggested that L-NNA elevated blood pressure by inhibiting the basal or flow-induced release of nitric oxide from the endothelium that is causing a reduction in vascular smooth muscle tone. The smaller effect of L-NNA in WKY was due to weak smooth muscle tone, while the smaller effect in SHRSP and M-SHRSP is due to impaired function of endothelium.
Yamamoto
K
K
The Life Science Institute, Kinki University, Osaka-Sayama, Japan. reshyper@med.kindai.ac.jp
Shimamura
K
K
Sekiguchi
F
F
Sunano
S
S
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013045:Species Specificity; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D019335:Nitroarginine; D009569:Nitric Oxide