KATP+-channels modulate gill resistance in the rainbow trout (Onchorhyncus mukiss)

Michael P. Smith, Kenneth R. Olson

Research output: Contribution to journalArticle

Abstract

Opening of ATP-sensitive K+ channels (KATP+) in vascular smooth muscle allows K+ efflux with subsequent hyperpolarization, closure of voltage-sensitive Ca2+ channels (VOCs), and ensuing relaxation. KATP+ have been implicated as regulators of resting vascular tone as well as metabolic sensors which mediate vascular responsiveness. The potent vasoconstrictor peptide endothelin-1 (ET-1) may also participate in regulation of vascular tone. In previous work from this laboratory ET-1 potently contracted isolated vessels, elevated input pressure in isolated perfused gills and reduced dorsal aortic pressure in conscious trout, possibly through a gill constriction. Maximally vasorelaxant doses of the KATP+ opener pinacidil (PNC), the guanylate cyclase activator sodium nitroprusside (SNP) and the VOC blacker Verapamil (VER) relaxed unstimulated efferent branchial arteries by 46, 15 and 4%, respectively. PNC, SNP or VER pretreatment resulted in significant attenuation (p≤.05), mild attenuation or paradoxical enhancement of maximal ET-1 tension, respectively. In the untreated perfused gill, PNC reduced input pressure while SNP and VER did not. Furthermore, only PNC pretreatment fully offset subsequent input pressure elevations due to ET-1 and only PNC was effective in reversing ET-1 effects. This data suggests that KATP+ are important physiological modulators of resting tone and vasoresponsiveness in gill resistance elements of the trout.

Original languageEnglish (US)
Pages (from-to)A31
JournalFASEB Journal
Volume11
Issue number3
StatePublished - Dec 1 1997

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ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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