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Denervation of carotid chemoreceptors decreases blood pressure in an ovine model of renovascular hypertension
Author(s) -
Ramchandra Rohit,
George Bindu,
McBryde Fiona,
Tromp Tycho,
Chang Joshua
Publication year - 2019
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.2019.33.1_supplement.560.4
Subject(s) - medicine , carotid sinus , baroreflex , denervation , blood pressure , baroreceptor , renal artery , renovascular hypertension , cardiology , heart rate , anesthesia , mean arterial pressure , endocrinology , kidney
Background Hypertension is a major health problem of pandemic proportions that is often inadequately controlled, warranting development of new treatments. There is increasing evidence that hypertension is initiated and maintained by elevated sympathetic nerve activity. There is also strong evidence that aberrant afferent signalling from carotid chemoreceptors promotes sympathoexcitation and hypertension. We hypothesized that hypertension is associated with activation of carotid chemoreceptors and that carotid sinus denervation (CSD) would reduce blood pressure. Methods Adult ewes either underwent unilateral renal artery clipping or sham surgery. Three weeks later, baroreflex control of heart rate was examined and the contribution of sympathetic mechanisms to hypertension was determined using hexamethonium (125 mg/hr). The mean arterial pressure and renal blood flow response to activation of carotid chemoreceptors was determined in both groups. In a second surgery conducted in hypertensive animals only, the carotid sinus nerve was severed bilaterally (CSD) (n=6) or left intact (sham, n=6) and the effect on blood pressure was examined. Results Unilateral renal artery clipping induced hypertension (mean arterial pressure 109 ± 2 vs 91 ± 3 mmHg in shams, p<0.001). The pressor response and the renal vasoconstriction response to chemoreceptor activation was augmented in hypertensive animals compared to the normal group (for e.g. MAP response, 15 ± 1 vs 7 ± 2 mmHg, p<0.05). CSD decreased MAP (−17 ± 1 vs +2 ± 1 mmHg in shams, p<0.0001) and shifted the heart rate baroreflex curve to the left. The contribution of the autonomic nerves to hypertension was elevated in hypertensive animals compared to normal (−19 ± 2 vs −11 ± 2 mmHg, p<0.05) and CSD reduced this contribution. Discussion In conclusion, we have shown that hypertension in our large animal model is associated with activation of carotid chemoreceptors and that bilateral CSD lowers arterial pressure. Our data implicates the carotid chemoreceptors in the maintenance of renovascular hypertension. Support or Funding Information Funded by the University of Auckland Faculty Research Development Fund and the Health Research Council of New Zealand. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .