Article date: June 1996
By: Gudarz Sadeghi‐Hashjin, Gert Folkerts, Paul A.J. Henricks, Peet G.F. Loo, Ilse E.M. Dik, Frans P. Nijkamp, in Volume 118, Issue 3, pages 466-470
Sodium nitroprusside (SNP) completely relaxed the guinea‐pig isolated, perfused trachea in a concentration‐dependent manner. Although SNP was less potent by about 2 orders of magnitude, its maximal effect was 25% higher compared to isoprenaline.
SNP (3.2 μm) increased cyclic GMP levels by 300% and relaxed guinea‐pig isolated, perfused trachea by 54%. The SNP‐induced relaxations of the preparations were not affected by the guanylate cyclase inhibitor, methylene blue. Moreover, zaprinast, a cyclic GMP‐specific phosphodiesterase inhibitor which was supposed to enhance SNP‐induced relaxations, decreased the maximal relaxation by 22% (P < 0.001).
In contrast, 8Br‐cyclic GMP (10 μm) increased the cyclic GMP levels by 1100% without inducing a marked relaxation.
SNP (10 μm) and S‐nitroso‐N‐acetylpenicillamine (SNAP; a direct donor of nitric oxide; 10 μm), relaxed the tissues by 75% and 25%, respectively, without any nitric oxide (NO) release by SNP (< 1 pmol 100 μl−1), but a substantial NO release by SNAP (560 pmol 100 μl−1).
It is concluded that the SNP‐induced tracheal relaxations are probably not mediated by cyclic GMP and NO.
Sodium nitroprusside (SNP) completely relaxed the guinea‐pig isolated, perfused trachea in a concentration‐dependent manner. Although SNP was less potent by about 2 orders of magnitude, its maximal effect was 25% higher compared to isoprenaline.
SNP (3.2 μm) increased cyclic GMP levels by 300% and relaxed guinea‐pig isolated, perfused trachea by 54%. The SNP‐induced relaxations of the preparations were not affected by the guanylate cyclase inhibitor, methylene blue. Moreover, zaprinast, a cyclic GMP‐specific phosphodiesterase inhibitor which was supposed to enhance SNP‐induced relaxations, decreased the maximal relaxation by 22% (P < 0.001).
In contrast, 8Br‐cyclic GMP (10 μm) increased the cyclic GMP levels by 1100% without inducing a marked relaxation.
SNP (10 μm) and S‐nitroso‐N‐acetylpenicillamine (SNAP; a direct donor of nitric oxide; 10 μm), relaxed the tissues by 75% and 25%, respectively, without any nitric oxide (NO) release by SNP (< 1 pmol 100 μl−1), but a substantial NO release by SNAP (560 pmol 100 μl−1).
It is concluded that the SNP‐induced tracheal relaxations are probably not mediated by cyclic GMP and NO.
DOI: 10.1111/j.1476-5381.1996.tb15426.x
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