Insulin-induced changes in beta-adrenergic response: an experimental study in the isolated rat papillary muscle.
Am J Hypertens
; 18(3): 348-53, 2005 Mar.
Article
en En
| MEDLINE
| ID: mdl-15797652
ABSTRACT
BACKGROUND:
The aim was to investigate the ability of insulin to modulate the response to beta-adrenergic action on myocardial contractility, assessed as percentage changes of developed tension, in isolated rat papillary muscle.METHODS:
Dose-response curves for isoproterenol, calcium, and forskolin were constructed in an incremental fashion with the presence or absence of insulin at the dose of 50 muU/mL. Dose-response curves for isoproterenol on insulin background were also assessed in the presence and absence of a selective antagonist for beta(2)-adrenoceptor, ICI, at the dose of 5 x 10(-8) mol/L.RESULTS:
Insulin did not modify the dose-response curve to calcium (EC(50) 1.4 +/- 0.4 mmol/Lfor insulin, n = 8 v 1.5 +/- 0.3 mmol/L for control, n = 8; P = not significant), whereas it was able to shift to the left the dose-response curve and reduce significantly the EC(50) of isoproterenol (EC(50) 0.2 +/- 0.2 nmol/L for insulin, n = 13 v 1.1 +/- 0.4 nmol/L for control, n = 12; P < .01). ICI shifted to the right dose-response curve of isoproterenol and increased about 10-fold the EC(50) value of isoproterenol, but insulin was still able to shift to the left dose-response curve of isoproterenol and to reduce significantly the EC(50) of isoproterenol also in the presence of ICI (EC(50) 11.0 +/- 1.5 nmol/L for ICI, n = 7 v 1.9 +/- 0.8 nmol/L for ICI + insulin, n = 7; P < .01). Insulin did not modify the dose-response curve to forskolin.CONCLUSIONS:
Our results suggest that the insulin-induced modulation of contractility is calcium independent and insulin leads to a supersensitization on the beta(1)-adrenoceptors without effects on beta-adrenoceptor independent adenylate cyclase-related pathway.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Músculos Papilares
/
Receptores Adrenérgicos beta
/
Hipoglucemiantes
/
Insulina
Límite:
Animals
Idioma:
En
Revista:
Am J Hypertens
Asunto de la revista:
ANGIOLOGIA
Año:
2005
Tipo del documento:
Article
País de afiliación:
Italia