Intracerebroventricular administration of hypertonic sodium chloride solution reduces the sensitivity of the baroreceptor heart reflex in anaesthetized rats.
Intracerebroventricular (i.c.v.) infusion of hypertonic sodium chloride solution increased blood pressure (BP) and shortened heart period (interbeat-interval: IBI) that is why an impairment in baroreflex regulation is believed to be part of that process. Therefore, in anaesthetized rats (1.35 g urethane/kg BW) the baroreceptor-heart reflex (BHR) was tested before and during i.c.v. infusion (15 min) of isotonic or hypertonic (0.6 M, 1.0 M) sodium chloride solution by inducing an acute BP rise by i.v. pressoric agents (phenylephrine, methoxamine). The evoked reflex prolongation of the IBI was taken to estimate the sensitivity of that BHR (delta ms/mm Hg). Whilst i.c.v. infusion of isotonic sodium chloride solution did not affect BHR sensitivity, hypertonic sodium chloride solution not only elevated BP and shortened IBI but also reset and impaired the BHR. Therefore, an increased central sensitivity to sodium chloride might not only increase BP but also impair the buffering capacity of the BHR against this rise and in this way support development of hypertension.
Brattström
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A
Institute of Physiology, Medical School, Magdeburg, FRG.
Appenrodt
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E
Brattström
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A
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D011311:Pressoreceptors / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage* / Q000494:pharmacology; D013223:Statistics as Topic
D012462:Saline Solution, Hypertonic