Exercise changes regional vascular control by commissural NTS in spontaneously hypertensive rats

Abstract

Ogihara CA, Schoorlemmer GHM, Levada AC, Pithon-Curi TC, Curi R, Lopes OU, Colombari E, Sato MA. Exercise changes regional vascular control by commissural NTS in spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 299: R291-R297, 2010. First published April 21, 2010 doi:10.1152/ajpregu.00055.2009.-Inhibition of the commissural nucleus of the solitary tract (commNTS) induces a fall in sympathetic nerve activity and blood pressure in spontaneously hypertensive rats (SHR), which suggests that this subnucleus of the NTS is a source of sympathoexcitation. Exercise training reduces sympathetic activity and arterial pressure. The purpose of the present study was to investigate whether the swimming exercise can modify the regional vascular responses evoked by inhibition of the commNTS neurons in SHR and normotensive Wistar-Kyoto (WKY) rats. Exercise consisted of swimming, 1 h/day, 5 days/wk for 6 wks, with a load of 2% of the body weight. The day after the last exercise session, the rats were anesthetized with intravenous ␣-chloralose, tracheostomized, and artificially ventilated. The femoral artery was cannulated for mean arterial pressure (MAP) and heart rate recordings, and Doppler flow probes were placed around the lower abdominal aorta and superior mesenteric artery. Microinjection of 50 mM GABA into the commNTS caused similar reductions in MAP in swimming and sedentary SHR (Ϫ25 Ϯ 6 and Ϫ30 Ϯ 5 mmHg, respectively), but hindlimb vascular conductance increased twofold in exercised vs. sedentary SHR (54 Ϯ 8 vs. 24 Ϯ 5%). GABA into the commNTS caused smaller reductions in MAP in swimming and sedentary WKY rats (Ϫ20 Ϯ 4 and Ϫ16 Ϯ 2 mmHg). Hindlimb conductance increased fourfold in exercised vs. sedentary WKY rats (75 Ϯ 2% vs. 19 Ϯ 3%). Therefore, our data suggest that the swimming exercise induced changes in commNTS neurons, as shown by a greater enhancement of hindlimb vasodilatation in WKY vs. SHR rats in response to GABAergic inhibition of these neurons.GABA; cardiovascular; citrate synthase THE NUCLEUS OF THE SOLITARY tract (NTS) is the primary site in the central nervous system that receives the afferents arising from arterial baro-and chemoreceptors (10, 15). The intermediate NTS receives inputs particularly from arterial baroreceptors, but some of these afferents achieve the commNTS (10, 16). The commNTS also receives inputs from arterial chemoreceptors, and seems to be highly sensitive to carotid chemoreceptor stimulation (8, 9, 11).The possible role of the commNTS as a source of sympathoexcitation was first shown by Nelson et al. (33), which demonstrated that nanoliter injections of L-glutamate into the commNTS evoke elevations in heart rate and arterial pressure mediated by the sympathetic nervous system. Electrolytic lesions or chemical inhibition of the commNTS have been shown to markedly decrease the splanchnic sympathetic nerve activity and arterial pressure in spontaneously hypertensive rats (SHR), which suggested that this subnucleus of the NTS contains neurons tonically active in S...

Cardiovascular and autonomic modulation by the central nervous system after aerobic exercise training

“…The commNTS also receives inputs from arterial chemoreceptors and seems to be highly sensitive to carotid chemore-www.bjournal.com.br Braz J Med Biol Res 44 (9) 2011 ceptor stimulation. A recent study observed that swimming exercise induced changes in commNTS neurons that were demonstrated by a greater enhancement of hindlimb vasodilatation in WKY vs SHR rats in response to the GABAergic inhibition of these neurons (55). This study reinforces the view that the CNS participates in the cardiovascular adaptations to exercise training and proposes a differential vascular regulation mediated by the CNS.…”

Exercise Training Lowers the Enhanced Tonically Active Glutamatergic Input to the Rostral Ventrolateral Medulla in Hypertensive Rats

“…Importantly, EXT normalizes the carotid body chemoreflex by preventing an increase in afferent carotid body chemoreceptor activity in rabbit with chronic heart failure . A recent study also shows that swimming exercise enhances the GABAergic inhibition in the commNTS neurons of SHR . The above evidence indicates that ExT leads to a reduction in afferent activity as well as neuronal activity in the commNTS.…”

Chronic exercise modulates RAS components and improves balance between pro- and anti-inflammatory cytokines in the brain of SHR

“…S oleus muscles from both legs of each animal were collected and stored at –80 °C for determination of CS activity (n=8 per group), a measure of muscle oxidative capacity, to determine the efficacy of the training protocol [47]. CS activity was measured from whole muscle homogenate by using commerically available citrate synthase activity assay kit (Sigma Aldrich).…”