title: Characterization of the role of endogenous nitric oxide in myogenic vascular oscillations during cooling-evoked hemodynamic perturbations of rats.
abstract: Rapid immersion of a rat's limbs into 4 °C water, a model of cold stress, can elicit hemodynamic perturbations (CEHP). We previously reported that CEHP is highly relevant to sympathetic activation and nitric oxide production. This study identifies the role of nitric oxide in CEHP. Conscious rats were pretreated with the nitric oxide synthase inhibitor L-NAME (NG-nitro-l-arginine methyl ester) alone or following the removal of sympathetic influences using hexamethonium or guanethidine. Rats were then subjected to a 10 min cold-stress trial. Hemodynamic indices were telemetrically monitored throughout the experiment. The analyses included measurements of systolic blood pressure; heart rate; dicrotic notch; short-term cardiovascular oscillations and coherence between blood pressure variability and heart rate variability in regions of very low frequency (0.02-0.2 Hz), low frequency (0.2-0.6 Hz), and high frequency (0.6-3.0 Hz). We observed different profiles of hemodynamic reaction between hexamethonium and guanethidine superimposed on L-NAME, suggesting an essential role for a functional adrenal medulla release of epinephrine under cold stress. These results indicate that endogenous nitric oxide plays an important role in the inhibition of sympathetic activation and cardiovascular oscillations in CEHP.
authors.affiliation: a Division of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan.|b School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yi-Hsien
authors.initials: YH
authors.lastname: Lin
authors.affiliation: c Department of Physiology, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yia-Ping
authors.initials: YP
authors.lastname: Liu
authors.affiliation: a Division of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Lin
authors.affiliation: d Department of Electrical Engineering, National Central University, Taoyuan, Taiwan.
authors.forename: Po-Lei
authors.initials: PL
authors.lastname: Lee
authors.affiliation: a Division of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan.
authors.forename: Che-Se
authors.initials: CS
authors.lastname: Tung
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects; D058639:Cold-Shock Response / Q000502:physiology*; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester
keywords: activation du système sympathique; cardiovascular oscillations; cold stress; hemodynamic perturbations; nitric oxide; oscillations cardiovasculaires; oxyde nitrique; perturbations hémodynamiques; stress par le froid; sympathetic activation