Effects of N omega-monomethyl-L-arginine on short-term RR interval and systolic blood pressure oscillations.
The role of endothelium-derived nitric oxide (EDNO) in short-term regulation of RR interval and arterial blood pressure (BP) in conscious rats was studied with N omega-monomethyl-L-arginine (L-NMMA). RR interval and systolic BP (SBP) variability was investigated by spectral analysis procedures. L-NMMA infused intravenously (i.v.) at 1.2 mg/kg/min elicited a clear increase in blood pressure (BP), RR interval (RRI), and respiratory rate. The main spectral modifications observed during L-NMMA infusion were (a) an increase in power of lower frequency (LF, 0.02-0.20 Hz) systolic BP (SBP) oscillations, (b) a decrease in the power of middle frequency (MF, 0.20-0.60 Hz), SBP oscillations, (c) an increase in the power of respiratory (high-frequency, HF) RR oscillations, and (d) an increase in the SBP-RR correlation in the LF band. These results suggest that L-NMMA infusion induced a rearrangement in the lower frequency oscillations of SBP, in which a decrease in sympathetic activity appears to be involved. The increase in HF oscillations of the RR interval appears to be a consequence of the increase in vagal activity in response to the increase in SBP induced by L-NMMA infusion. The suggested autonomic nervous system alterations could account for the increase in the SBP-RRI correlation in the LF band after L-NMMA administration.
Cordero
J J
JJ
Department of Physiology, Faculty of Medicine, University of La Laguna, Tenerife, Spain.
González
J
J
Feria
M
M
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D004562:Electrocardiography / Q000187:drug effects*; D008297:Male; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000502:physiology; D019323:omega-N-Methylarginine
D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine