Transgenic overexpression of insulin-like growth factor I prevents streptozotocin-induced cardiac contractile dysfunction and beta-adrenergic response in ventricular myocytes.
J Endocrinol
; 180(1): 175-82, 2004 Jan.
Article
em En
| MEDLINE
| ID: mdl-14709156
ABSTRACT
Diabetic cardiomyopathy is characterized by cardiac dysfunction and altered level/function of insulin-like growth factor I (IGF-I). Both endogenous and exogenous IGF-I have been shown to effectively alleviate diabetes-induced cardiac dysfunction and oxidative stress. This study was designed to examine the effect of cardiac overexpression of IGF-I on streptozotocin (STZ)-induced cardiac contractile dysfunction in mouse myocytes. Both IGF-I heterozygous transgenic mice and their wild-type FVB littermates were made diabetic with a single injection of STZ (200 mg/kg, i.p.) and maintained for 2 weeks. The following mechanical indices were evaluated in ventricular myocytes peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocity of shortening/relengthening (+/- dL/dt). Intracellular Ca2+ was evaluated as resting and peak intracellular Ca2+ levels, Ca2+-induced Ca2+ release and intracellular Ca2+ decay rate (tau). STZ led to hyperglycemia in FVB and IGF-I mice. STZ treatment prolonged TPS and TR90, reduced Ca2+-induced Ca2+ release, increased resting intracellular Ca2+ levels and slowed tau associated with normal PS and +/- dL/dt. All of which, except the elevated resting intracellular Ca2+, were prevented by the IGF-I transgene. In addition, myocytes from STZ-treated FVB mice displayed an attenuated contractile response to the beta-adrenergic agonist isoproterenol, which was restored by the IGF-I transgene. Contractile response to the alpha-adrenergic agonist phenylephrine and angiotensin II was not affected by either STZ treatment or IGF-I. These results validate the beneficial role of IGF-I in diabetic cardiomyopathy, possibly due to an improved beta-adrenergic response.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fator de Crescimento Insulin-Like I
/
Miócitos Cardíacos
/
Diabetes Mellitus Experimental
/
Contração Miocárdica
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Endocrinol
Ano de publicação:
2004
Tipo de documento:
Article
País de afiliação:
Estados Unidos