These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Role of calcium-activated potassium channels and cyclic nucleotides on pulmonary vasoreactivity to serotonin.
    Author: Barman SA.
    Journal: Am J Physiol; 1997 Jul; 273(1 Pt 1):L142-7. PubMed ID: 9252551.
    Abstract:
    The role of Ca(2+)-activated K+ channel modulation and cyclic nucleotide second messenger signal transduction in the canine pulmonary vascular response to serotonin was determined in the isolated blood-perfused dog lung. Pulmonary vascular resistances and compliances were measured using vascular occlusion techniques. Serotonin (10(-5) M) significantly increased precapillary and postcapillary resistance and significantly decreased total vascular compliance by decreasing large vessel compliance and middle compartment compliance. Tetraethylammonium ions (TEA+; 1 mM), an inhibitor of Ca(2+)-activated K+ channels, significantly potentiated the pressor effect to serotonin on both the pulmonary arteries and pulmonary veins. Pretreatment with the guanosine 3',5'-cyclic monophosphate (cGMP)/adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (10(-5) M), the cell membrane-permeable analog of cAMP, dibutyryl-cAMP (10(-5) M), or the cAMP-dependent vasodilator isoproterenol (10(-5) M) inhibited the serotonergic response on both the arteries and veins, which was reversed by TEA+. In contrast, the stable membrane-permeable analog of cGMP, 8-bromo-cGMP (10(-5) M), had no effect on serotonin. These results indicate that there is a basal level of vasorelaxation in canine pulmonary blood vessels that is mediated by Ca(2+)-activated K+ channel activity and that inhibition of these K+ channels increases pulmonary vascular tone and potentiates the pulmonary vasoactive response to serotonin. Also, these data suggest that cAMP-induced pulmonary vasodilation is mediated primarily by Ca(2+)-activated K+ channels and that activation of these specific K+ channels attenuates the pressor response to serotonin. Thus an important relationship appears to exist between the cAMP second messenger system and Ca(2+)-activated K+ channels in canine pulmonary vasoreactivity.
    [Abstract] [Full Text] [Related] [New Search]