Animal models are a useful tool, for example, in the study of hypertension, but its use requires robust knowledge and well characterized models in order to extrapolate the obtained results. Nitric oxide is an important regulator of vascular function and blood pressure. The chronic administration of nitric oxide synthase (NOS) inhibitors provides an animal experimental model of hypertension. Our study aims to investigate the hemorheological effects of (i) Nw-nitro-L-arginine methyl ester (L-NAME) added daily to Sprague-Dawley rats in drinking water and (ii) valsartan, an angiotensin II AT1-receptor antagonist, administration when the Sprague-Dawley rats acquired the hypertensive state. In three experimental groups (Control, Hypertensive and Valsartan) systolic blood pressure was measured and blood samples were collected for determination of erythrocyte membrane deformability and fluidity as well as blood and plasma viscosities. L-NAME intake induces an increase in the systolic blood pressure indicating the development of systemic hypertension. Concerning the hemorheological parameters, the erythrocyte deformability is decreased in the hypertensive animal group and on contrary the erythrocyte membrane fluidity increased being both parameters values reverted after valsartan administration. Valsartan also decreases the plasma and blood viscosities values obtained in the animal group which have acquired systemic hypertension after L-NAME intake. In conclusion, the angiotensin II AT1-receptor antagonist, valsartan, restores in hypertensive Sprague-Dawley rats LNAME- dependent their systolic blood pressure to the physiological values, as well as, normalized their hemorheological parameters values; due to the similarity effects to human essential hypertension we conclude that this can be a suitable animal model for hemorheological studies in the field of hypertension.

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