Effect of losartan on insulin plasma concentrations and LPL activity in adipose tissue of hypertensive rats.

ABSTRACT

The aim of this study is to determine the effect of losartan on insulin and angiotensin II (Ang II) concentrations in plasma as well as on lipoprotein lipase activity (LPL) and angiotensin II content in the adipose tissue of hypertensive rats. Fifty male rats were divided in five groups. Group A served as controls. Group B underwent renal artery stenosis. Group C were administered losartan (10 mg/kg/day) per os, while rats in group D were submitted to renal artery stenosis and were treated with losartan as above. Group E was used as sham-operated control. The animals were sacrificed at day 21. Blood samples were collected, and perirenal adipose tissue was isolated. Furthermore, adrenal's were removed and their relative weight (adrenal weight/body weight) was used as an index of sympathetic stimulation. According to our results, renovascular hypertension resulted in lower insulin concentrations and higher Ang II content in plasma. In hypertensive rats, LPL activity was decreased, while the adrenals' relative weight was elevated. On the other hand, losartan administration resulted in normalization of insulin concentrations in plasma and adrenals' relative weight, with consequent up regulation of LPL activity in adipose tissue. In conclusion, renovascular hypertension interferes in lipid metabolism by reducing LPL activity in adipose tissue, while losartan administration reverses this effect by enhancing insulin release and reducing sympathetic nervous system (SNS) stimulation.