Key result
Prior exposure to nitroglycerin induced marked tolerance to its vasorelaxant effects in rat aortic rings (20% vs 84% maximal relaxation, p<0.001), which was not reversed by N-acetylcysteine.
Why the study?
Does contraction with endothelin-1 or L-NMMA restore nitroglycerin-mediated relaxation in NTG-tolerant rat aortic rings?
Population
Rat aortic rings
Comparison
Pre-exposure to nitroglycerin or acetylcholine… vs Control rings without NTG pre-exposure
Design
Preclinical
Authors
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Questions sulfhydryl depletion hypothesis for nitroglycerin tolerance; leaves open whether endothelin-1 or L-NMMA modulation translates to humans.
Does contraction with endothelin-1 or L-NMMA restore nitroglycerin-mediated relaxation in NTG-tolerant rat aortic rings?
Absolute Event Rate: 20% vs 84%
p-value: p=<0.001
In rat aortic rings, nitroglycerin tolerance is likely not related to sulfhydryl depletion, and NTG-mediated relaxation can be restored by contraction with endothelin-1 or L-NMMA.
Lawson et al. (1996) studied Vascular tolerance to nitroglycerin. Nitroglycerin (NTG) vs. Control rings was evaluated on Maximal relaxation of norepinephrine-precontracted rat aortic rings (p=<0.001). Prior exposure to nitroglycerin induced marked tolerance to its vasorelaxant effects in rat aortic rings (20% vs 84% maximal relaxation, p<0.001), which was not reversed by N-acetylcysteine.
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