Abstract
There is a paradoxical alpha-adrenoceptor-mediated coronary vasoconstriction whenever there is adrenergic activation of the heart, as during cardiovascular reflexes or exercise. A previous study demonstrated that this paradoxical vasoconstriction helps maintain blood flow to the vulnerable inner layer of the left ventricular wall during exercise, but the mechanism for this effect was not elucidated. The purpose of the present investigation was to test the hypothesis that alpha-adrenoceptor-mediated vasoconstriction lessens the to-and-fro oscillation of blood flow that occurs in the coronary arterial tree during systole and diastole. Septal coronary artery blood velocity was measured in anesthetized open-chest dogs with a 20-MHz pulsed Doppler velocimeter. Systolic retrograde velocity and diastolic forward velocity were compared during norepinephrine infusion before and after alpha-adrenoceptor blockade with phenoxybenzamine. Systolic aortic pressure was held constant by aortic banding; heart rate was controlled by pacing at 80, 140, and 200 beats/min; and maximum left ventricular dP/dt was unchanged by alpha-blockade. At each pacing rate, systolic retrograde velocity was significantly greater after alpha-blockade, indicating th...Continue Reading
References
Nov 1, 1977·Circulation Research·R J Bache, F R Cobb
Mar 1, 1992·Cardiovascular Research·J WestbyK Grong
Jun 1, 1992·Circulation·M GotoF Kajiya
Apr 1, 1990·Physiological Reviews·J I Hoffman, J A Spaan
Feb 1, 1989·Circulation Research·W M ChilianM L Marcus
Nov 1, 1989·Circulation Research·H KanatsukaM L Marcus
Oct 1, 1987·Circulation·E O Feigl
Feb 1, 1988·Circulation Research·W M Chilian, P H Ackell
Feb 1, 1988·Circulation Research·A H Huang, E O Feigl
Nov 1, 1987·Circulation·F KajiyaT Fujiwara
Jan 1, 1983·Physiological Reviews·E O Feigl
Apr 1, 1982·Circulation Research·U J JohannsenM L Marcus
Jun 1, 1982·Circulation Research·W M Chilian, M L Marcus
Sep 1, 1981·Circulation Research·J A SpaanJ D Laird
Nov 1, 1993·Circulation Research·D BaumgartG Heusch
May 1, 1993·Circulation Research·T YadaF Kajiya
Jul 1, 1995·Basic Research in Cardiology·D D Gutterman, D A Morgan
Citations
Aug 25, 2005·Experimental Biology and Medicine·Pu ZongH Fred Downey
Jan 16, 2010·Journal of Applied Physiology·John V Tyberg
Mar 6, 2016·American Journal of Physiology. Heart and Circulatory Physiology·Christopher J ArthursC Alberto Figueroa
Oct 29, 2000·Journal of Applied Physiology·M W GormanE O Feigl
Jun 29, 2004·Journal of Applied Physiology·Johnathan D TuneEric O Feigl
Dec 17, 2009·Journal of Applied Physiology·Shawn B BenderM Harold Laughlin
Jan 15, 2002·American Journal of Physiology. Heart and Circulatory Physiology·Masayuki TakamuraMichel Lavallée
Mar 23, 2002·Experimental Biology and Medicine·Johnathan D TuneEric O Feigl
Mar 27, 2004·Experimental Biology and Medicine·Pu ZongH Fred Downey
May 31, 2003·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Craig S BrobergLowell E Davis
Nov 20, 2004·American Journal of Physiology. Heart and Circulatory Physiology·Eiji ToyotaWilliam M Chilian
Feb 24, 2004·Journal of Applied Physiology·Srinath SettyJohnathan D Tune
Jul 16, 2008·Physiological Reviews·Dirk J Duncker, Robert J Bache