ET-1 increases distensibility of acutely loaded myocardium: a novel ETA and Na+/H+ exchanger-mediated effect

• Type: Article in International Scientific Journal
• Date: 2003

Authors

Leite Moreira, AF (Author) FMUP; Bras Silva, C (Author) Other; Pedrosa, CA (Author) Other; Rocha Sousa, AA (Author) FMUP

Journal

Title: American Journal of Physiology - Heart and Circulatory Physiology

Vol. 284 No. 4

Pages: H1332-H1339

ISSN: 0363-6135

Publisher: American Physiological Society

Indexing

ISI Web of Knowledge - 27 Citations

Scopus - 32 Citations

Scientific classification

FOS: Medical and Health sciences > Clinical medicine

Other information

Authenticus ID: P-000-H3P

DOI: 10.1152/ajpheart.00715.2002

Abstract (EN): This study investigated, in rabbit papillary muscles (n = 61) and human auricular strips (n = 7), effects of endothelin-1 (ET-1; 0.1-10 nM) on diastolic myocardial properties. ET-1 (1 nM) was also given in the presence of selective ETA or ETB antagonism, nonselective ETA/ETB antagonism, and Na+/H+ exchanger inhibition. Effects of 6.3 mM Ca2+ were also studied. ET-1 dose dependently increased inotropism. In contrast to baseline, in the presence of ET-1, resting tension (RT) decreased, after an isometric twitch, 3.4 +/- 1.4, 6.9 +/- 1.5, and 12.5 +/- 3.1% with 0.1, 1, and 10 nM, respectively, reflecting an increase in myocardial distensibility. ET-1 effects were abolished with selective ETA as well as with nonselective ETA/ETB antagonism, whereas they were still present with ETB antagonism. Na+/H+ exchanger inhibition abolished ET-1 effects on distensibility, whereas it only partially inhibited positive inotropic effect. Ca2+ increased inotropism. to a similar extent to ET-1 (1 nM) but did not affect distensibility. ET-1 therefore increased diastolic distensibility of acutely loaded human and nonhuman myocardium. This effect is mediated by ETA receptors, requires Na+/H+ exchanger activation, and cannot be elicited by Ca2+.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8