Enhancement of apneic reflex induced by sumatriptan: Role of bronchopulmonary C‐fibers in rats

Abstract

Sumatriptan (Imigran®), an agonist of 5‐hydroxytryptophan (5HT)1B and 5HT1D receptors, is widely and effectively used to alleviate migraine headaches. Two of the most frequent side effects reported by patients are somatic hyperalgesia and chest discomfort. The chest syndromes are represented by chest tightness and dyspnea. Bronchopulmonary sensory C‐fibers innervate all levels of respiratory tract. Stimulation of the sensory fibers elicit airway reflexes including bronchoconstriction, shortness of breath, and dyspnea. This study was carried out to determine the effect of intravenous infusion of sumatriptan on sensitivity of ventilatory reflexes and bronchopulmonary sensory C‐fibers. In anesthetized, spontaneously breathing Brown‐Norway rats, the apneic response to right‐atrial injection of capsaicin was markedly enhanced 3 min after termination of sumatriptan infusion, which returned toward baseline within 80 min. In contrast, infusion of vehicle of sumatriptan failed to cause the enhancing effect. In our electrophysiological study, sumatriptan infusion did not influence the baseline activity of bronchopulmonary sensory C‐fibers in open‐chest, and artificially ventilated rats. However, these C‐fiber responses to right atrial injection of capsaicin were markedly potentiated 3 min after termination of sumatriptan infusion. The results suggest that sumatriptan enhances the excitability of bronchopulmonary sensory C‐fibers, which may, in turn, contribute to airway hypersensitivity.Support or Funding InformationSupported in part by grants TMU105‐AE1‐B17, MOST‐107‐2320‐B‐038‐041 and MOST‐107‐2320‐B‐038‐049‐MY3This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.