BACKGROUND: In streptozotocin-injected rats (STZ-rats), we previously demonstrated a role for angiotensin II (AT-II) in cardiac remodelling and insulin resistance partially counteracted by in vivo treatment with losartan, an AT-II receptor antagonist.We now aimed to investigate the effect of treating diabetic STZ-rats with losartan on diabetes vascular response to vasoconstrictors. METHODS: Male Wistar rats were randomly divided in four groups, two of them were assigned to receive losartan in the drinking water (20 mg/kg/day) until the experiment ending (3 weeks afterward). After 1 week, two groups, one of which receiving losartan, were injected in the tail vein with citrate buffer (normoglycemic, N and normoglycemic, losartan-treated, NL). The remaining received a single injection of streptozotocin (50 mg/kg in citrate i.v.) thus becoming diabetic (D) and diabetic losartan-treated (DL). Plasma glycaemia and blood pressure were measured in all animals before the sacrifice (15 days after diabetes induction).In aortic strips isolated from N, NL, D and DL rats we evaluated i) the isometric concentration-dependent contractile response to phenylephrine (Phe) and to AT-II; ii) the RhoA-kinase (ROCK1) activity and expression by enzyme-immunoassay and Western blot respectively. KEY RESULTS: The concentration-dependent contractile effect of Phe was similar in aortas from all groups, whereas at all concentrations tested, AT-II contraction efficacy was 2 and half and 1 and half times higher in D and DL respectively in comparison with N and NL. AT-II contracture was similarly reduced in all groups by AT-II receptor antagonists, irbesartan or irbesartan plus PD123319. HA-1077 (10 microM), an inhibitor of ROCK1 activity, reduced AT-II efficacy (Deltamg/mg tissue w.w.) by -3.5 +/- 1.0, -4.6 +/- 1.9, -22.1 +/- 2.2 and -11.4 +/- 1.3 in N, NL, D and DL respectively). ROCK1 activity and expression were higher in D than in N/NL and DL aortas. CONCLUSION AND IMPLICATIONS: Aortas isolated from STZ-rats present hyper-contracture to AT-II mainly dependent on the up-regulation of ROCK1 expression/activity. In vivo losartan treatment partially corrects AT-II hyper-contracture, limiting the increase in ROCK1 expression/activity. These data offer a new molecular mechanism supporting the rationale for using losartan in the prevention of diabetic vascular complications.

Losartan counteracts the hyper-reactivity to angiotensin II and ROCK1 over-activation in aortas isolated from streptozotocin-injected diabetic rats / Paola Failli;Chiara Alfarano;Sergio Franchi-Micheli;Edoardo Mannucci;Elisabetta Cerbai;Alessandro Mugelli;Laura Raimondi. - In: CARDIOVASCULAR DIABETOLOGY. - ISSN 1475-2840. - ELETTRONICO. - 8:(2009), pp. 1-10. [10.1186/1475-2840-8-32]

Losartan counteracts the hyper-reactivity to angiotensin II and ROCK1 over-activation in aortas isolated from streptozotocin-injected diabetic rats

FAILLI, PAOLA;MANNUCCI, EDOARDO;CERBAI, ELISABETTA;MUGELLI, ALESSANDRO;RAIMONDI, LAURA
2009

Abstract

BACKGROUND: In streptozotocin-injected rats (STZ-rats), we previously demonstrated a role for angiotensin II (AT-II) in cardiac remodelling and insulin resistance partially counteracted by in vivo treatment with losartan, an AT-II receptor antagonist.We now aimed to investigate the effect of treating diabetic STZ-rats with losartan on diabetes vascular response to vasoconstrictors. METHODS: Male Wistar rats were randomly divided in four groups, two of them were assigned to receive losartan in the drinking water (20 mg/kg/day) until the experiment ending (3 weeks afterward). After 1 week, two groups, one of which receiving losartan, were injected in the tail vein with citrate buffer (normoglycemic, N and normoglycemic, losartan-treated, NL). The remaining received a single injection of streptozotocin (50 mg/kg in citrate i.v.) thus becoming diabetic (D) and diabetic losartan-treated (DL). Plasma glycaemia and blood pressure were measured in all animals before the sacrifice (15 days after diabetes induction).In aortic strips isolated from N, NL, D and DL rats we evaluated i) the isometric concentration-dependent contractile response to phenylephrine (Phe) and to AT-II; ii) the RhoA-kinase (ROCK1) activity and expression by enzyme-immunoassay and Western blot respectively. KEY RESULTS: The concentration-dependent contractile effect of Phe was similar in aortas from all groups, whereas at all concentrations tested, AT-II contraction efficacy was 2 and half and 1 and half times higher in D and DL respectively in comparison with N and NL. AT-II contracture was similarly reduced in all groups by AT-II receptor antagonists, irbesartan or irbesartan plus PD123319. HA-1077 (10 microM), an inhibitor of ROCK1 activity, reduced AT-II efficacy (Deltamg/mg tissue w.w.) by -3.5 +/- 1.0, -4.6 +/- 1.9, -22.1 +/- 2.2 and -11.4 +/- 1.3 in N, NL, D and DL respectively). ROCK1 activity and expression were higher in D than in N/NL and DL aortas. CONCLUSION AND IMPLICATIONS: Aortas isolated from STZ-rats present hyper-contracture to AT-II mainly dependent on the up-regulation of ROCK1 expression/activity. In vivo losartan treatment partially corrects AT-II hyper-contracture, limiting the increase in ROCK1 expression/activity. These data offer a new molecular mechanism supporting the rationale for using losartan in the prevention of diabetic vascular complications.
2009
8
1
10
Paola Failli;Chiara Alfarano;Sergio Franchi-Micheli;Edoardo Mannucci;Elisabetta Cerbai;Alessandro Mugelli;Laura Raimondi
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/656881
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