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β‐Adrenoreceptors in the ventricle of the rainbow trout
Author(s) -
Shiels Holly A,
Fenna Andrew,
Pellowe Sarita,
Robinson Ryan,
Taylor Rebecca
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1071.7
Subject(s) - isoprenaline , endocrinology , medicine , ventricle , myocyte , stimulation , salbutamol , agonist , receptor , antagonist , biology , trout , chemistry , fish <actinopterygii> , asthma , fishery
Stimulation of cardiac β adrenergic receptors (βARs) results in increased cardiac function. Despite significant research into mammalian βAR signalling, little is known of βAR signalling in the teleost heart. We applied pharmacological agents known to stimulate βARs in mammalian ventricular myocytes, to myocytes isolated from the rainbow trout heart and assessed changes in the Ca current and in cell shortening. In agreement with previous work, isoprenaline (50 nM and 1 uM) increased % cell shortening and the amplitude of Ca current. Salbutamol (1 uM and 50 uM) a β2‐AR partial agonist also increased these parameters above control levels but not to the same extent as isoprenaline. The β2‐AR antagonist (ICI‐188,551, 1 uM) significantly decreased the contractile and ionic responses to isoprenaline and almost completely abolished the responses to salbutamol. These experiments were repeated in myocytes pre‐incubated with Pertussis toxin (PTX) to inhibit Gi‐signalling and while there was a trend for PTX‐ treated cells to show greater responses than control cells, this was not statistically resolvable. Real time qPCR was used to investigate the βAR subtypes responsible for these functional observations in trout ventricle. mRNA was expressed for β1, β2, β3a, β3b¬‐ARs, with the β2AD the most prominent consistent with the pharmacology.