Swimming Exercise Changes Hemodynamic Responses Evoked by Blockade of Excitatory Amino Receptors in the Rostral Ventrolateral Medulla in Spontaneously Hypertensive Rats

Exercise training reduces sympathetic activity in hypertensive humans and rats. We hypothesized that the swimming exercisewould change the neurotransmission in the rostral ventrolateral medulla (RVLM), a key region involved in sympathetic outflow, and hemodynamic control in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Bilateral injections of kynurenic acid (KYN) were carried out in the RVLM in sedentary- (S-) or exercised- (E-) SHR and WKY rats submitted to swimming for 6 weeks. Rats were alpha-chloralose anesthetized and artificially ventilated, with Doppler flow probes around the lower abdominal aorta and superior mesenteric artery. Injections into the RVLM were made before and after i.v. L-NAME (nitric oxide synthase, NOS, inhibitor). Injections of KYN into the RVLM elicited a major vasodilation in the hindlimbmore than in the mesenteric artery in E-SHR compared to S-SHR, but similar decrease in arterial pressure was observed in both groups. Injections of KYN into the RVLM after i.v. L-NAME attenuated the hindlimb vasodilation evoked by KYN and increased the mesenteric vasodilation in ESHR. Swimming exercise can enhance the hindlimb vasodilation mediated by peripheral NO release, reducing the activation of neurons with EAA receptors in the RVLM in SHR.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Nucleo de Estudo Pesquisa e Assessoria a Pesquisa da Faculdade de Medicina do ABC (NEPAS, FMABC)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FMABC, Dept Physiol, BR-09060650 Santo Andre, SP, BrazilFed Univ São Paulo UNIFESP, Dept Physiol, BR-04023901 São Paulo, BrazilFed Univ São Paulo UNIFESP, Dept Pharmacol, BR-04044020 São Paulo, BrazilSão Paulo State Univ UNESP, Sch Dent, Dept Pathol & Physiol, BR-14801385 Araraquara, SP, BrazilFed Univ São Paulo UNIFESP, Dept Physiol, BR-04023901 São Paulo, BrazilFed Univ São Paulo UNIFESP, Dept Pharmacol, BR-04044020 São Paulo, BrazilFAPESP: 06/60842-1Web of Scienc

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

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 alpha-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 (-25 +/- 6 and -30 +/- 5 mmHg, respectively), but hindlimb vascular conductance increased twofold in exercised vs. sedentary SHR (54 +/- 8 vs. 24 +/- 5%). GABA into the commNTS caused smaller reductions in MAP in swimming and sedentary WKY rats (-20 +/- 4 and -16 +/- 2 mmHg). Hindlimb conductance increased fourfold in exercised vs. sedentary WKY rats (75 +/- 2% vs. 19 +/- 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.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo[06/60842-1]Nucleo de Estudo Pesquisa e Assessoria a Pesquisa da Faculdade de Medicina do ABCNucleo de Estudo Pesquisa e Assessoria a Pesquisa da Faculdade de Medicina do ABCCAPES Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES