AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 3 678-R686, Copyright © 1994 by American Physiological Society

ARTICLES

Nonuniform enhancement of baroreflex sensitivity by atrial natriuretic peptide in conscious rats and dogs

R. L. Woods, C. A. Courneya and G. A. Head
Baker Medical Research Institute, Prahran, Victoria, Australia.

The influence of atrial natriuretic peptide (ANP) on the blood pressure (BP)-heart rate (HR) baroreflex was studied in conscious chronically instrumented dogs and rats. In both species, sigmoid steady-state baroreflex curves were constructed from the baroreflex changes in HR to alternating slow injections of vasopressor and vasodepressor drugs. When this method was used in dogs, ANP caused a small but significant (P < 0.05) enhancement of the sensitivity (22 +/- 10%) and curvature (26 +/- 10%) of the baroreflex, which was without a change in HR range. In rats, ANP had no significant effect on any baroreflex parameter derived from steady-state curves. By contrast, in the same rats, fast reflex HR responses to rapid increases in BP (ramp) exposed a substantial (81 +/- 21%) ANP-induced enhancement of baroreflex sensitivity. Contribution from arterial vs. nonarterial afferents to the baroreflex is not uniform between these two techniques (steady state reflects largely arterial baroreceptor input, ramp evokes a greater proportion of cardiopulmonary afferent activation). The present study demonstrated that baroreceptor HR reflex responses to ANP depend on the baroreflex techniques employed and probably exposed a selectivity by ANP for nonarterial baroreflex pathways.

This article has been cited by other articles:

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				J. H. Ricketts and G. A. Head A five-parameter logistic equation for investigating asymmetry of curvature in baroreflex studies Am J Physiol Regulatory Integrative Comp Physiol, August 1, 1999; 277(2): R441 - R454. [Abstract] [Full Text] [PDF]

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