Investigation of the Role of AT2 Receptors in the Nucleus Tractus Solitarii of Normotensive Rats in Blood Pressure Control

Figures

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  FIGURE 1. Histological verification of the probe localization within the intermediate NTS by a neutral red staining compared against an anatomic atlas (Paxinos and Watson, 1998).

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  FIGURE 2. Effect of perfusion of C21 (120–240 min) within the NTS on the extracellular glutamate (A) and GABA (B) concentrations in normotensive freely moving Wistar rats. Baseline values for glutamate and GABA were respectively, 262 ± 80 and 9 ± 8 nM (C21 0.05 μg/μl/h); 327 ± 270 and 19 ± 8 nM (C21 0.1 μg/μl/h). Baseline values for glutamate and GABA during L-NAME (0.4 μg/μl/h) and C21 (0.05 μg/μl/h) + candesartan (0.5 ng/μl/h) perfusion were respectively, 247 ± 87 and 15 ± 8 nM; 614 ± 274 and 10 ± 8 nM. Data are presented as the mean percentage of baseline levels ± SEM. Statistical analysis is performed using the Friedman test for repeated measures with Dunnett’s post hoc multiple comparison. Local L-NAME (0.4 μg/μl/h) perfusion significantly decreased glutamate at time point 220 min (∗p < 0.05) and GABA levels at time point 140 min (∗∗∗p < 0.001) and 240 min (∗p < 0.05) compared to mean baseline values.

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  FIGURE 3. Effect of perfusion of C21(120–240 min) within the NTS on MAP (A) and HR (B). Baseline MAP and HR levels were respectively, 86 ± 4 mmHg and 367 ± 35 bpm (C21 0.05 μg/μl/h); 93 ± 4 mmHg and 398 ± 42 bpm (C21 0.1 μg/μl/h). Baseline MAP and HR levels during clonidine (0.15 mg/μl/h) and C21 (0.05 μg/μl/h) + candesartan (0.5 ng/μl/h) perfusion were respectively, 90 ± 3 mmHg and 429 ± 72 bpm; 93 ± 7 mmHg and 404 ± 30 bpm. Data are presented as the mean percentage of baseline levels ± SEM. Statistical analysis is performed using the Friedman test for repeated measures with Dunnett’s post hoc multiple comparison. Local perfusion of clonidine (15 mg/μl/h) significantly decreased MAP levels at time point 110 min (∗p < 0.05) compared to mean baseline values.