Abstract
This study characterizes the effects of L-arginine and NG-monomethyl L-arginine on dilator responsiveness of vascular tissue from Wistar-Kyoto rats and stroke-prone spontaneously hypertensive rats. Rings of abdominal aorta were suspended in tissue baths for measurement of isometric force. After contraction induced by phenylephrine, cumulative addition of acetylcholine, L-arginine, or A23187 to the muscle bath caused a similar relaxation of aortic rings in both animal groups. To test the hypothesis that arginine metabolism is altered in hypertension, aortic rings were incubated with NG-monomethyl L-arginine. NG-monomethyl L-arginine (10-300 μM) did not affect contractile responses to phenylephrine (10-10 to 10-4 M) in either animal group (EC50, 10-7 M). Exposure of aortic rings to NG-monomethyl L-arginine resulted in a greater inhibition of relaxation response to acetylcholine (10-10 to 10-6 M) in hypertensive animals. NG-monomethyl L-arginine (300 μM) caused complete inhibition of relaxation to acetylcholine in the hypertension group. Incubation with L-arginine (10-100 μM) overcame the inhibition of acetylcholine-induced relaxation produced by NG-monomethyl L-arginine in both groups. Exposure of aortic ring segments to NG-monomethyl L-arginine attenuated relaxation responses to A23187 (10-10 to 3×10-6 M) in both groups. L-Arginine-induced reversal of the inhibitory effect of NG-monomethyl L-arginine on the relaxation responses to A23187 was similar between groups. We conclude that the inhibitory effect of NG-monomethyl L-arginine on endothelium-derived relaxing factor production in response to acetylcholine is greater in stroke-prone spontaneously hypertensive rats as compared with Wistar-Kyoto rats. This finding reflects differences in L-arginine metabolism in genetic hypertension that may be an important factor in contributing to altered vascular reactivity.
Original language | English (US) |
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Pages (from-to) | 435-441 |
Number of pages | 7 |
Journal | Hypertension |
Volume | 19 |
Issue number | 5 |
State | Published - May 1992 |
Externally published | Yes |
Keywords
- Arginine
- Endothelium
- Genetic hypertension
- Rat studies
ASJC Scopus subject areas
- Internal Medicine