ISSN:
1440-1681
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
SUMMARY 1. Rises and falls in mean arterial (MAP) and pulse (PP) pressures from the resting value were evoked by intravenous injections of phenylephrine and glyceryl trinitrate, and were related to the reflexly evoked changes in heart period (HP; pulse interval).2. The steady-state properties of the baroreceptor-heart rate reflex were examined by deriving MAP-HP curves in a group of twenty-three healthy normotensive subjects, and in two groups of sixteen and eight subjects with essential hypertension of different severity. Each group was subdivided into two subgroups according to age: (i) 18–30 years; (ii) 33–57 years. The MAP-HP curves are sigmoid and each is characterized by its median blood pressure (BP50), average gain (Ḡ1) and heart period range (HPR).3. In a given age group, the curves are ‘reset’ about a higher BP50 with increasing severity of hypertension. There is progressive reduction in HPR (to 80–55% of normotensive HPR) due to lowering of the upper HP plateau, which probably indicates impairment of function of the vagal component of the reflex. In three out of four hypertensive groups, Ḡ is also significantly reduced to between 60 and 30% of Ḡ of normotensive subjects of the same age.4. The effect of age on the curve parameters is independent of the effects due to hypertension. For a given MAP, Ḡ and HPR are lower in older than in younger subjects.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1440-1681.1974.tb00528.x
