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Inhibition of the vagal component of the baroreceptor‐cardioinhibitory reflex by angiotensin III in dogs and sheep.
Author(s) -
Lumbers E R,
Potter E K
Publication year - 1983
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1983.sp014568
Subject(s) - baroreceptor , angiotensin ii , renin–angiotensin system , medicine , efferent , endocrinology , reflex , reflex bradycardia , blood pressure , angiotensin receptor , chemistry , heart rate , afferent
Angiotensin II inhibits baroreceptor‐evoked activity in cardiac vagal motoneurones. Because angiotensin III [( des‐1‐Asp ]angiotensin II) is a less potent pressor agent than angiotensin II, and has been reported not to share some of the actions of angiotensin II within the central nervous system, its influence on central vagal pathways was examined here. In unanaesthetized sheep equipressor doses of angiotensins II and III similarly inhibited the baroreceptor‐cardioinhibitory reflex, a reflex which is almost wholly dependent on cardiac vagal activity. In anaesthetized dogs, equipressor doses of angiotensin II and III were equally effective in inhibiting the cardiac vagal activity usually evoked by rises in arterial pressure. This was established by direct recordings of activity in single cardiac vagal efferent nerve fibres. Direct recordings from single baroreceptor nerves in anaesthetized dogs showed that the angiotensins do not depress the receptor responses to elevations in blood pressure. It is concluded that equipressor doses of angiotensin III and angiotensin II inhibit central vagal pathways to the same extent.