Impairment of nitric oxide pathway by intravascular hemolysis plays a major role in mice esophageal hypercontractility: reversion by soluble guanylyl cyclase stimulator

• Published in: The Journal of pharmacology and experimental therapeutics 2018-11, Vol.367 (2), p.194-202
• Main Authors: Silva, Fabio Henrique, Fertrin, Kleber Yotsumoto, Alexandre, Eduardo Costa, Calmasini, Fabiano Beraldi, Franco-Penteado, Carla Fernanda, Costa, Fernando Ferreira
• Format: Article
• Language: English
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1124/jpet.118.249581

Paroxysmal nocturnal hemoglobinuria (PNH) patients display exaggerated intravascular hemolysis and esophageal disorders. Since excess hemoglobin in the plasma causes reduced nitric oxide (NO) bioavailability and oxidative stress, we hypothesized that esopagheal contraction may be impaired by intravascular hemolysis. This study aimed to analyze the alterations of the esophagus contractile mechanisms in a murine model of exaggerated intravascular hemolysis induced by phenylhydrazine (PHZ). For comparative purposes, sickle cell disease (SCD) mice were also studied, a less severe intravascular hemolysis model. Esophagus rings were dissected free and placed in organ baths. Plasma hemoglobin was higher in PHZ compared to SCD mice, as expected. The contractile responses produced by carbachol (CCh), KCl and EFS were superior in esophagus from PHZ compared to control, but remained unchanged in SCD mice. Preincubation with NO-independent sGC stimulator BAY 41-2272 (1 μM) completely reversed the increased contractile responses to CCh, KCl and EFS in PHZ mice, but remained unchanged with prior treatment with NO donor sodium nitroprusside (300 μM). Protein expression of 3-NT and 4-HNE increased in esophagus from PHZ mice, suggesting a state of oxidative stress. In eNOS-/-, the contractile responses elicited by KCl and CCh were increased in the esophagus, but remained unchanged with the intravascular hemolysis induced by PHZ. In conclusion, our results show that esophagus hypercontractile state occurs in association with lower NO bioavailability due to exaggerated hemolysis intravascular and oxidative stress. Moreover, our study supports the hypothesis that esophageal disorders in PNH patients are secondary to intravascular hemolysis affecting the NO-cGMP pathway.