An analysis of the nitrate‐like and K channel opening actions of KRN2391 in canine coronary arterial smooth muscle

Yuji Okada, Teruyuki Yanagisawa, Norio Taira

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30 Citations (Scopus)


To clarify the mechanism of action of KRN2391, a new vasodilator containing a nitroxy group, its effects on intracellular Ca2+ concentration ([Ca2+]i) and force of contraction in canine coronary artery were compared with those of two derivatives lacking the nitro group. KRN2391, its hydroxy and acetoxy derivative (Compound 2 and Compound 3, respectively) partially reduced [Ca2+]i in 5 or 30 mm KCl physiological salt solution (PSS), effects which were antagonized by glibenclamide. No KRN2391‐induced change in [Ca2+]i was observed in 90 mm KCl‐PSS. The order of potency in reducing [Ca2+]i and inhibiting the contracture in 30 mm KCl‐PSS was: KRN2391 > Compound 3 > Compound 2. In 30 mm KCl‐PSS, KRN2391 shifted the [Ca2+]i‐force relationship so that a greater increase in [Ca2+]i was needed to produce force. Compounds 2 and 3 were ineffective. The [Ca2+]i‐force curve obtained in 90 mm KCl‐PSS was shifted to the right by KRN2391 (10−4 m). The ability of KRN2391 to reduce the force of contraction in both 30 mm and 90 mm KCl‐PSS was inhibited by 10−5 m methylene blue. KRN2391 inhibited U46619‐induced contractions; this effect was associated with a reduction of [Ca2+]i, which decreased below the basal level. Thus, KRN2391 is a potent vasodilator in canine coronary artery. It possesses nitrate‐like and potassium channel opening actions and can be designated as a nitrate‐potassium channel opener (N‐K) hybrid. The denitrate derivatives of KRN2391 are specific K channel openers. The nitroxy moiety in KRN2391 is important for not only its action as a nitrate but also its potency as a K channel opener. 1991 British Pharmacological Society

Original languageEnglish
Pages (from-to)829-838
Number of pages10
JournalBritish Journal of Pharmacology
Issue number4
Publication statusPublished - 1991 Dec
Externally publishedYes


  • K channel opener
  • KRN2391
  • N‐K hybrid
  • dog coronary artery
  • fura‐2
  • glibenclamide
  • intracellular calcium concentration
  • nitrate
  • relaxation

ASJC Scopus subject areas

  • Pharmacology


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