Synergistic activation of salmon cardiac function by endothelin and beta-adrenergic stimulation.
The aim was to find out the effects of endothelin-1 (ET-1) in salmon (Salmo salar) cardiac contractile and endocrine function and its possible interaction with beta-adrenergic regulation. We found that ET-1 has a positive inotropic effect in salmon heart. ET-1 (30 nM) increased the contraction amplitude 17+/-4.7% compared with the basal level. beta-Adrenergic activation (isoprenaline, 100 nM) increased contraction amplitude 30+/-13.1%, but it did not affect the contractile response to ET-1. ET-1 (10 nM) stimulated the secretion of salmon cardiac natriuretic peptide (sCP) from isolated salmon ventricle (3.3+/-0.14-fold compared with control) but did not have any effect on ventricular sCP mRNA. Isoprenaline alone (0.1-1,000 nM) did not stimulate sCP release, but ET-1 (10 nM) together with isoprenaline (0.1 nM) caused a significantly greater increase of sCP release than ET-1 alone (5.4+/-0.07 vs. 3.3+/-0.14 times increase compared with control). The effects on the contractile and secretory function could be inhibited by a selective ETA-receptor antagonist BQ-610 (1 microM), whereas ETB-receptor blockage (by 100 nM BQ-788) enhanced the secretory response. Thus ET-1 is a phylogenetically conserved regulator of cardiac function, which has synergistic action with beta-adrenergic stimulation. The modulatory effects of ET-1 may therefore be especially important in situations with high beta-adrenergic tone.
Department of Physiology, POB 5000, FIN-90014, University of Oulu, Oulu, Finland.
Heidi
H
Vierimaa
Jarkko
J
Ronkainen
Heikki
H
Ruskoaho
Olli
O
Vuolteenaho
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000494:pharmacology*; D005260:Female; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology; D045265:Natriuretic Peptides / Q000235:genetics / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020317:Salmo salar
D000318:Adrenergic beta-Agonists; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D029941:Fish Proteins; D045265:Natriuretic Peptides; D009842:Oligopeptides; D010880:Piperidines; D012333:RNA, Messenger; C403482:cardiac natriuretic peptide, Salmo salar; C087220:BQ 610; C086539:BQ 788; D007545:Isoproterenol