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Influence of Spinal Neurotransmission on Renal Sympathetic Nerve Activity in Renovascular Hypertension
Author(s) -
Campos Ruy R,
Milanez Maycon I. O.,
Nishi Erika E,
Bergamaschi Cássia T
Publication year - 2017
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.31.1_supplement.lb801
Subject(s) - medicine , rostral ventrolateral medulla , renovascular hypertension , losartan , blood pressure , endocrinology , angiotensin ii , spinal cord , anesthesia , heart rate , psychiatry
Studies performed in our laboratory showed a higher glutamate and angiotensin II type 1 (AT1) receptors activation in the rostral ventrolateral medulla (RVLM) that may lead to sympathoexcitation in renovascular hypertensive rats . However, the role of the spinal cord neurons on the renal sympathoexcitation remains unclear in this model. Thus, we aimed to assess the influence of spinal glutamatergic (ionotropic receptors) and AT1 receptors on the renal sympathetic nerve activity (RSNA) and blood pressure (BP) in renovascular hypertension. Male Wistar (250–300g) rats were divided into two independent groups: CTL‐control rats (n=11) and 2K1C‐hypertensive rats (n=9). All experiments were approved by the Institutional Ethical Committee . Renovascular hypertension was induced by clipping the renal artery with a silver clip. After six weeks, a polyethylene catheter (PE‐10) was inserted into the subarachnoid space and advanced to the T10–11 vertebrae level in urethane‐anaesthetized rats (1,2 g/Kg, iv). The effects of intrathecal (i.t.) injection of kynurenic acid (KYN) (2 μl, 160 nmol) or losartan (Los) (2 μl, 2nmol) on BP and RSNA were analyzed for 2 consecutive hours. KYN i.t. injection induced a larger and significant fall on RSNA in the 2K1C compared with control group (CTL × 2K1C: −8 ± 3 × −52 ± 9* spikes/s after 120′). Los i.t. injection also evoked a larger and significant fall in RSNA in the 2K1C compared with control group from 80' after Los i.t. administration (CTL × 2K1C – 80 min: −10 ± 2 × −32 ± 6*; 100 min: −15 ± 4 × −37 ± 9*; 120 min: −12 ± 5 × −37 ± 8* spikes/s). KYN decreased BP similarly in CTL and 2K1C groups, however, Los significantly decreased BP in the 2K1C group only. Therefore, our data show that ionotropic spinal cord excitatory aminoacid and AT1 receptors play an important role in the control of RSNA in the 2K1C model that may contribute to the maintenance of hypertension. The origin of those projections remains unclear. *p<0,05. Support or Funding Information CNPq, FAPESP (13/22522‐9), CAPES.