Role of the area postrema in angiotensin II modulation of baroreflex control of heart rate in conscious mice.
This study reports the effects of angiotensin II (ANG II), arginine vasopression (AVP), phenylephrine (PE), and sodium nitroprusside (SNP) on baroreflex control of heart rate in the presence and absence of the area postrema (AP) in conscious mice. In intact, sham-lesioned mice, baroreflex-induced decreases in heart rate due to increases in arterial pressure with intravenous infusions of ANG II were significantly less than those observed with similar increases in arterial pressure with PE (slope: -3.0 +/- 0.9 vs. -8.1 +/- 1.5 beats x min(-1) x mmHg(-1)). Baroreflex-induced decreases in heart rate due to increases in arterial pressure with intravenous infusions of AVP were the same as those observed with PE in sham animals (slope: -5.8 +/- 0.7 vs. -8.1 +/- 1.5 beats x min(-1) x mmHg(-1)). After the AP was lesioned, the slope of baroreflex inhibition of heart rate was the same whether pressure was increased with ANG II, AVP, or PE. The slope of the baroreflex-induced increases in heart rate due to decreases in arterial blood pressure with SNP were the same in sham- and AP-lesioned animals. These results indicate that, similar to other species, in mice the ability of ANG II to acutely reset baroreflex control of heart rate is dependent on an intact AP.
Xue
Baojian
B
Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri 65211, USA.
Gole
Hope
H
Pamidimukkala
Jaya
J
Hay
Meredith
M
D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D031608:Area Postrema / Q000187:drug effects / Q000502:physiology*; D001127:Arginine Vasopressin / Q000494:pharmacology / Q000502:physiology; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D016014:Linear Models; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014851:Wakefulness
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000804:Angiotensin II; D001127:Arginine Vasopressin