Parasympathetic impairment of baroreflex control of heart rate in Dahl S rats. Am J Physiol 1990 Jul;259(1 Pt 2):R76-83
Date
07/01/1990Pubmed ID
2375431DOI
10.1152/ajpregu.1990.259.1.R76Scopus ID
2-s2.0-0025003680 (requires institutional sign-in at Scopus site) 18 CitationsAbstract
To test the hypothesis that impaired baroreflex control of heart rate in Dahl salt-sensitive (S) rats is due to an impairment of the parasympathetic limb of the bradycardic response, baroreflex sensitivity was evaluated in conscious, chronically instrumented Dahl S and salt-resistant (R) animals. Sensitivity was impaired in Dahl S rats when bolus doses of phenylephrine were administered (0.863 +/- 0.042 vs. 1.43 +/- 0.055 ms/mmHg), but it was not different than in R rats when tested with sodium nitroprusside. When the sensitivities before and after blocking the parasympathetic nervous system with atropine were compared, it was revealed that 82% of the reflex bradycardia resulting from bolus doses of phenylephrine was due to the parasympathetic nervous system, whereas the majority (73%) of the bradycardia induced by 5-min infusions of phenylephrine was due to withdrawal of sympathetic tone. Neither baroreflex sensitivity to infusions of phenylephrine (73% sympathetic) or to infusions after atropine (100% sympathetic) were significantly different between S and R rats. Therefore, the impairment of the heart rate reflex in Dahl S rats is due to an impairment of the parasympathetic limb of the response. In addition, a high-salt diet before the development of hypertension did not alter baroreflex sensitivity in either Dahl S or R rats.
Author List
Whitescarver SA, Ott CE, Kotchen TAMESH terms used to index this publication - Major topics in bold
AnimalsAtropine Derivatives
Blood Pressure
Dose-Response Relationship, Drug
Heart Rate
Hypertension
Injections
Male
Parasympathetic Nervous System
Parasympatholytics
Rats
Sodium Chloride
Sodium, Dietary
Sympathetic Nervous System
