Volume 8, Number 2, June 2007

Cross-talk related to insulin and angiotensin II binding on myocardial remodelling in diabetic rat hearts
Wael M Maharsy, Lina N Kadi, Nahla G Issa, Khalil M Bitar, Asdghig H Der-Boghossian, Roy Abrahamian, Anwar B Bikhazi

This study focused on the regulation and affinity modulation of angiotensin II (Ang II) binding to its receptor subtypes (AT₁- and AT₂-receptor) in the coronary endothelium (CE) and cardiomyocytes (CM) of Sprague-Dawley male rats in normal (N), normal treated with losartan (NL), streptozotocin-induced diabetic (D), insulin-treated diabetic (DI), losartan-treated diabetic (DL), and diabetic co-treated with insulin and losartan (DIL). Heart perfusion was used to estimate Ang II binding affinity (τ=1/k_-n) to its receptor subtypes on CE and CM. Diabetes decreased τ value on CE and increased it on CM as compared to normal. In DL group, the τ value decreased on CE but was normalised on CM. Insulin treatment alone (DI) or with losartan (DIL) restored t to normal on both CE and CM. Western blot results for AT₁-receptor density showed an increase in diabetics compared to normal with no normalising effect with insulin treatment. The AT₁-receptor density was normalised in the diabetic groups treated with losartan +/- insulin. Results for AT₂-receptor regulation revealed a significant difference between untreated (D) and losartan-treated (DL, DIL) diabetic groups. All of these data show the interrelated pathway and cross-talk between insulin and Ang II system indicating potentially negative effects on the diabetic heart.

JRAAS 2007;8:59-65.

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