title: Nitric oxide inhibition in paraventricular nucleus on cardiovascular and autonomic modulation after exercise training in unanesthetized rats.
abstract: It is well known that regular physical exercise alter cardiac function and autonomic modulation of heart rate variability (HRV). The paraventricular nucleus of hypothalamus (PVN) is an important site of integration for autonomic and cardiovascular responses, where nitric oxide (NO) plays an important role. The aim of our study was to evaluate the cardiovascular parameters and autonomic modulation by means of spectral analysis after nitric oxide synthase (NOS) inhibition in the PVN in conscious sedentary (S) or swimming trained (ST) rats. After swimming training protocol, adult male Wistar rats, instrumented with guide cannulas to PVN and femoral artery and vein catheters were submitted to mean arterial pressure (MAP) and heart rate (HR) recording. At baseline, the physical training induced a resting bradycardia (S: 374±5, ST: 346±1bpm) and promoted adaptations in HRV characterized by an increase in high-frequency oscillations (HF; 26.43±6.91 to 88.96±2.44) and a decrease in low-frequency oscillations (LF; 73.57±6.91 to 11.04±2.44) in normalized units. The microinjection of N(ω)-nitro-l-arginine methyl ester (l-NAME) in the PVN of sedentary and trained rats promoted increase in MAP and HR. l-NAME in the PVN did not significantly alter the spectral parameters of HRV of sedentary animals, however in the trained rats increased LF oscillations (11.04±2.44 to 27.62±6.97) and decreased HF oscillations (88.96±2.44 to 72.38±6.97) in normalized units compared with baseline. Our results suggest that NO in the PVN may collaborate to cardiac autonomic modulation after exercise training.
authors.affiliation: Department of Physiological Sciences, Center of Biological Sciences, State University of Londrina, Londrina, Paraná, Brazil.
authors.forename: Rosiane Batista
authors.initials: RB
authors.lastname: Mastelari
authors.forename: Hugo Celso Dutra
authors.initials: HC
authors.lastname: de Souza
authors.forename: Adriane
authors.initials: A
authors.lastname: Lenhard
authors.forename: Fernando Morgan
authors.initials: FM
authors.lastname: de Aguiar Corrêa
authors.forename: Marli Cardoso
authors.initials: MC
authors.lastname: Martins-Pinge
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008845:Microinjections; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013550:Swimming / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester