Do natriuretic peptides modify arterial baroreflexes in sheep?
While atrial and B-type natriuretic peptides (ANP and BNP) have been shown to enhance reflex responses attributed to cardiac vagal afferents, their effects on arterial baroreceptor reflex function remain controversial. The actions of C-type natriuretic peptide (CNP) in this regard are unknown. To clarify their actions on arterial baroreflexes, we tested whether i.v. infusions of ANP, BNP or CNP at 10 pmol kg(-1) min(-1) modified the steady-state mean arterial blood pressure-heart rate (MAP-HR) relationship in conscious sheep. At this dose, all three natriuretic peptides are known to enhance the cardiac chemoreflex response to phenylbiguanide (Bezold-Jarisch reflex). Sigmoid MAP-HR relationships were constructed from the steady-state responses to alternating injections of vasopressor (phenylephrine, 1-15 microg kg(-1)) and vasodepressor agents (nitroprusside, 1-15 microg kg(-1)) in the absence and presence of infused ANP, BNP or CNP (tested in random order at least 1 week apart). No parameter of the steady-state baroreflex relationship was significantly altered by infusion of any of the three natriuretic peptides. We conclude that in conscious sheep, normal arterial baroreceptor-HR reflex function prevails in the presence of moderate doses of ANP, BNP or CNP.
Thomas
Colleen J
CJ
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Victoria 3010, Australia.
Woods
Robyn L
RL
D000818:Animals; D001158:Arteries / Q000294:innervation*; D009320:Atrial Natriuretic Factor / Q000008:administration & dosage / Q000494:pharmacology*; D017704:Baroreflex / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D007262:Infusions, Intravenous; D020097:Natriuretic Peptide, Brain / Q000008:administration & dosage / Q000494:pharmacology*; D020098:Natriuretic Peptide, C-Type / Q000008:administration & dosage / Q000494:pharmacology*; D012756:Sheep
D020097:Natriuretic Peptide, Brain; D020098:Natriuretic Peptide, C-Type; D009320:Atrial Natriuretic Factor