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Increased expression of AT2 receptors in the nucleus of the solitary tract improves baroreflex function in renovascular hypertensive rats.
Author(s) -
Blanch Graziela T,
FreiriaOliveira Andre H,
Rigatto Katya,
Li Hongwei,
Colombari Eduardo,
Sumners Colin,
Colombari Debora S A
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.927.10
Subject(s) - baroreflex , phenylephrine , renovascular hypertension , endocrinology , medicine , solitary tract , reflex , blood pressure , baroreceptor , sodium nitroprusside , receptor , heart rate , nitric oxide
Renovascular hypertensive (2K1C) rats exhibit impaired baroreflexes. Here we studied the effects of increased AT2R expression in the nucleus of the solitary tract (NTS) on baroreflex function of 2K1C rats. The left renal artery was partially obstructed in male Holtzman rats (150–180g) using a silver clip (0.2 mm width). Three weeks later, rats were microinjected in the NTS with either AAV2‐CBA‐AT2R or AAV2‐CBA‐eGFP to elicit chronic increases in AT2R or GFP (control) expression respectively. Thirty days later, femoral artery and vein were cannulated to measure mean arterial pressure (MAP) and heart rate (HR) and perform drug infusions, respectively. The next day, phenylephrine (5 μg/kg, iv) and sodium nitroprusside (30 μg/kg, iv) were used to elicit respective pressor and depressor responses in conscious rats. Reflex HR responses were analyzed to each 10 mmHg change in MAP. Baseline MAP in 2K1C‐AT2R rats (173 ± 7 mmHg) was lower than in 2K1C‐GFP rats (199 ± 9 mmHg; p <0.05). 2K1C‐GFP rats exhibited a significant impairment of the baroreflex (slope: −0.95 ± 0.05, vs. sham‐GFP −1.37 ± 0.06, p<0.05), which was improved in the 2K1C‐AT2R rats (slope: −1.44 ± 0.07). Baroreflex in 2K1C‐AT2R was similar to sham‐AT2R rats (slope: −1.56 ± 0.06) or sham‐GFP. The results suggest that AT2R over expression in the NTS of 2K1C rats improves baroreflex and this may contribute to the reduction in blood pressure observed in these animals. Supported by: PNPD/CAPES, NIH and FAPESP/PRONEX.