Cardiovascular risk factors in L-NAM E hypertension

ABSTRACT

In a previous study, hypertension was induced by administration of L-NAME for 1, 2 and 4 weeks. Hypertension was prevented when L-NAME was combined with L-arginine but not with dipyridamole. To study the changes in ECG, cardiac weights and plasma lipids associated with L-NAME hypertension. Wistar rats were allocated into a control group, 3 groups of rats that received L-NAME [20 mg/kg] for 1, 2 and 4 weeks, and 2 other groups that received L-NAME in the same dose for 2 weeks combined with L-arginine [40mg/kg] or dipyridamole [3mg/ kg]. The absolute weight of left ventricle [LV] and whole heart [WH] were significantly increased in L-NAME 4 weeks group, but such significant increase was lost when corrected for body weight [LV/BW and WH/BW]. In L-NAME and L-arginine 2 weeks group, there was no change in absolute or relative weights, whereas in the L-NAME and dipyridamole 2 weeks group, there was significant decrease in LV, WH and LV/BW. Concerning ECG parameters, there was no significant difference amongst control group and L-NAME I, 2 and 4 weeks groups as regards P-R interval, QRS complex and R-wave voltage. Both Q-To and Q-Tc intervals were significantly shortened in L-NAME 4 weeks group than control, L-NAME I week and 2 weeks groups. In L-NAME and L-arginine 2 weeks group, P-R interval was significantly shorter than control group. Also, L-NAME and dipyridamole 2 weeks group showed significant in R wave voltage than control and L-NAME 2 weeks groups. Treatment for 2 weeks with L-arginine or dipyridamole shortened Q-To and Q-Tc than control or L-NAME 2 weeks groups. In NAME-treated rats for I, 2 and 4 weeks, there was no significant changes in plasma levels of total cholesterol, HDL-cholesterol and LDL- cholesterol, nor atherogenic index or triglycerides. L-NAME hypertension up to 4 weeks duration was not associated with cardiac hypertrophy or ECG changes. Also, the lipid profile was not significantly modified from the normal pattern