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Role of cardiac hypertrophy in reducing the sensitivity of cardiopulmonary reflex control of renal sympathetic nerve activity in spontaneously hypertensive rats.
Clin Exp Pharmacol Physiol. 2008 Sep; 35(9):1104-8.CE

Abstract

The gain of the volume-sensitive cardiopulmonary reflex (VSCR) is impaired in spontaneously hypertensive rats (SHR). Sensitivity of VSCR control of efferent renal sympathetic nerve activity (RSNA) in SHR is restored when cardiac hypertrophy and hypertension are reduced by enalapril treatment. The present study investigated which of these two parameters, cardiac hypertrophy or hypertension, has more influence on the impairment of VSCR control of RSNA in SHR. Rats (SHR or Wistar-Kyoto (WKY) rats) were treated with enalapril (10 mg/kg per day; SHRE and WKYE groups, respectively) or hydralazine (5 mg/kg per day; SHRH and WKYH groups, respectively) mixed in their food for 1 month. Control SHR and WKY rats were fed a normal diet. After the treatment regimen, the VSCR was evaluated by determining the decrease in RSNA elicited by acute isotonic saline volume expansion. Mean arterial pressure (MAP) was assessed via an intrafemural catheter and cardiac hypertrophy was determined by the left ventricular (LV) weight/bodyweight (BW) ratio. Afferent baroceptor nerve activity (BNA) was also evaluated during volume expansion to verify participation of the baroreflex. Volume expansion produced an attenuated renal sympathoinhibitory response in SHR compared with WKY rats. Enalapril treatment restored the volume expansion-induced decrease in RSNA in SHRE (-41 +/- 8%) compared with WKY rats (-44 +/- 3%). Although both enalapril and hydralazine treatment reduced MAP in SHR (P < 0.01; 126 +/- 5, 133 +/- 6 and 160 +/- 6 mmHg in SHRE, SHRH and SHR, respectively), hydralazine did not restore the sensitivity of VSCR control of RSNA in SHRH. Spontaneously hypertensive rats with established hypertension had a higher LV/BW ratio compared with WKY rats (3.22 +/- 0.14 vs 1.98 +/- 0.06 mg/g, respectively; P < 0.01). Enalapril reduced the LV/BW ratio in SHRE (2.30 +/- 0.07 mg/g; P < 0.01). Although hydralazine reduced LV hypertrophy, there was a weaker reduction in SHRH (2.68 +/- 0.04 mg/g; P < 0.05) compared with SHRE. There was no statistically significant difference among the WKY rat, WKYE and WKYH groups (P > 0.05). There was no change in afferent BNA during volume expansion in normal or hypertensive animals. Taken together, these results indicate that the impairment of VSCR control of RSNA in the SHR model of hypertension correlates better with the magnitude of cardiac hypertrophy than the level of arterial pressure.

Authors+Show Affiliations

Department of Physiological Sciences, Centre of Health Sciences, Federal University of Espírito Santo, Vitória, Brazil.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18788121

Citation

de Andrade, Tadeu Uggere, et al. "Role of Cardiac Hypertrophy in Reducing the Sensitivity of Cardiopulmonary Reflex Control of Renal Sympathetic Nerve Activity in Spontaneously Hypertensive Rats." Clinical and Experimental Pharmacology & Physiology, vol. 35, no. 9, 2008, pp. 1104-8.
de Andrade TU, Abreu GR, Moysés MR, et al. Role of cardiac hypertrophy in reducing the sensitivity of cardiopulmonary reflex control of renal sympathetic nerve activity in spontaneously hypertensive rats. Clin Exp Pharmacol Physiol. 2008;35(9):1104-8.
de Andrade, T. U., Abreu, G. R., Moysés, M. R., de Melo Cabral, A., & Bissoli, N. S. (2008). Role of cardiac hypertrophy in reducing the sensitivity of cardiopulmonary reflex control of renal sympathetic nerve activity in spontaneously hypertensive rats. Clinical and Experimental Pharmacology & Physiology, 35(9), 1104-8.
de Andrade TU, et al. Role of Cardiac Hypertrophy in Reducing the Sensitivity of Cardiopulmonary Reflex Control of Renal Sympathetic Nerve Activity in Spontaneously Hypertensive Rats. Clin Exp Pharmacol Physiol. 2008;35(9):1104-8. PubMed PMID: 18788121.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Role of cardiac hypertrophy in reducing the sensitivity of cardiopulmonary reflex control of renal sympathetic nerve activity in spontaneously hypertensive rats. AU - de Andrade,Tadeu Uggere, AU - Abreu,Gláucia R, AU - Moysés,Margareth R, AU - de Melo Cabral,Antônio, AU - Bissoli,Nazaré S, PY - 2008/9/13/pubmed PY - 2009/1/17/medline PY - 2008/9/13/entrez SP - 1104 EP - 8 JF - Clinical and experimental pharmacology & physiology JO - Clin. Exp. Pharmacol. Physiol. VL - 35 IS - 9 N2 - The gain of the volume-sensitive cardiopulmonary reflex (VSCR) is impaired in spontaneously hypertensive rats (SHR). Sensitivity of VSCR control of efferent renal sympathetic nerve activity (RSNA) in SHR is restored when cardiac hypertrophy and hypertension are reduced by enalapril treatment. The present study investigated which of these two parameters, cardiac hypertrophy or hypertension, has more influence on the impairment of VSCR control of RSNA in SHR. Rats (SHR or Wistar-Kyoto (WKY) rats) were treated with enalapril (10 mg/kg per day; SHRE and WKYE groups, respectively) or hydralazine (5 mg/kg per day; SHRH and WKYH groups, respectively) mixed in their food for 1 month. Control SHR and WKY rats were fed a normal diet. After the treatment regimen, the VSCR was evaluated by determining the decrease in RSNA elicited by acute isotonic saline volume expansion. Mean arterial pressure (MAP) was assessed via an intrafemural catheter and cardiac hypertrophy was determined by the left ventricular (LV) weight/bodyweight (BW) ratio. Afferent baroceptor nerve activity (BNA) was also evaluated during volume expansion to verify participation of the baroreflex. Volume expansion produced an attenuated renal sympathoinhibitory response in SHR compared with WKY rats. Enalapril treatment restored the volume expansion-induced decrease in RSNA in SHRE (-41 +/- 8%) compared with WKY rats (-44 +/- 3%). Although both enalapril and hydralazine treatment reduced MAP in SHR (P < 0.01; 126 +/- 5, 133 +/- 6 and 160 +/- 6 mmHg in SHRE, SHRH and SHR, respectively), hydralazine did not restore the sensitivity of VSCR control of RSNA in SHRH. Spontaneously hypertensive rats with established hypertension had a higher LV/BW ratio compared with WKY rats (3.22 +/- 0.14 vs 1.98 +/- 0.06 mg/g, respectively; P < 0.01). Enalapril reduced the LV/BW ratio in SHRE (2.30 +/- 0.07 mg/g; P < 0.01). Although hydralazine reduced LV hypertrophy, there was a weaker reduction in SHRH (2.68 +/- 0.04 mg/g; P < 0.05) compared with SHRE. There was no statistically significant difference among the WKY rat, WKYE and WKYH groups (P > 0.05). There was no change in afferent BNA during volume expansion in normal or hypertensive animals. Taken together, these results indicate that the impairment of VSCR control of RSNA in the SHR model of hypertension correlates better with the magnitude of cardiac hypertrophy than the level of arterial pressure. SN - 1440-1681 UR - https://www.unboundmedicine.com/medline/citation/18788121/Role_of_cardiac_hypertrophy_in_reducing_the_sensitivity_of_cardiopulmonary_reflex_control_of_renal_sympathetic_nerve_activity_in_spontaneously_hypertensive_rats_ L2 - https://doi.org/10.1111/j.1440-1681.2007.04750.x DB - PRIME DP - Unbound Medicine ER -