American journal of physiology. Heart and circulatory physiology
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Am. J. Physiol. Heart Circ. Physiol. · Feb 2001
Cardiac sympathetic overactivity and decreased baroreflex sensitivity in L-NAME hypertensive rats.
The present study evaluated the possible changes in the autonomic control of heart rate in the hypertensive model induced by the inhibition of nitric oxide synthase. Rats were treated with N(G)-nitro-L-arginine methyl ester (L-NAME group) in the drinking water during 7 days, whereas control groups were treated with tap water (control group) or with the N(G)-nitro-D-arginine methyl ester (D-NAME group), an inactive isomer of the L-NAME molecule. The L-NAME group developed hypertension and tachycardia. ⋯ The spectral density power of heart rate, calculated using fast-Fourier transformation, indicated a reduced variability in the low-frequency band (0.20-0.60 Hz) for the L-NAME group. The baroreflex sensitivity was also attenuated in these animals when compared with the normotensive control or D-NAME group. Overall, these data indicate cardiac sympathetic overactivity associated with a decreased baroreflex sensitivity in L-NAME hypertensive rats.