Alpha 1-adrenergic blockade increases coronary blood flow during coronary hypoperfusion

Liang, I. Y. S.; Jones, C. E.

doi:10.1152/ajpheart.1985.249.6.h1070

Cited by 14 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, phentolamine prevented sympathetic poststenotic coronary constriction. The presence of alpha-adrenergic constrictor tone during coronary hypoperfusion was also confirmed by Liang and Jones [48]. The selective alpha~-adrenoceptor antagonist rauwolscine, in an equihypotensive dose, however, was equally effective as phentolamine ( Figure 3).…”

Section: Alpha-adrenergic Coronary Constriction and Myocardial Ischemiamentioning

confidence: 55%

Pharmacological mechanisms to attenuate sympathetically induced myocardial ischemia

Schulz

Guth

Heusch

1989

Cardiovasc Drug Ther

View full text Add to dashboard Cite

Distal to a coronary stenosis, resting myocardial blood flow and function can be maintained by a compensatory dilation of the poststenotic vascular bed and an increased collateral blood flow from adjacent coronary vessels. Under this condition, electrical stimulation of cardiac sympathetic nerves, as well as their activation during sympathoexcitatory reflexes and exercise, induces a poststenotic alpha 2-adrenoceptor-mediated coronary constriction and a beta-adrenoceptor-mediated, tachycardia-related redistribution of blood flow away from the ischemia myocardium. Thus, activation of cardiac sympathetic nerves can precipitate poststenotic myocardial ischemia. In experimental studies in anesthetized, vagotomized dogs, as well as in conscious, chronically instrumented dogs, selective alpha 2-adrenoceptor antagonists and calcium-channel blockade with nifedipine were able to attenuate the sympathetically induced poststenotic myocardial ischemia. Beta-adrenoceptor blockade with atenolol was only proven beneficial as long as there was a heart-rate reduction. Conversely, a specific bradycardic agent (ULFS-49) also exerted beneficial effects. Myocardial ischemia can activate cardiac sympathetic afferents and then, by a spinal reflex, can in turn activate sympathetic efferents and aggravate the severity of myocardial ischemia. This vicious cycle could be interrupted by segmental epidural anesthesia with procaine as well as by blockade of sympathoexcitation at the central nervous level with clonidine in anesthetized dogs.

show abstract

Section: Alpha-adrenergic Coronary Constriction and Myocardial Ischemiamentioning

confidence: 55%

Pharmacological mechanisms to attenuate sympathetically induced myocardial ischemia

Schulz

Guth

Heusch

1989

Cardiovasc Drug Ther

View full text Add to dashboard Cite

show abstract

“…8,9 Moreover, relief of ␣-adrenergic constrictor tone has clearly been shown to increase coronary blood flow in experimental models of hypoperfusion. 29 Whether ␣-adrenergic receptor blockers would improve resting dysfunction and contractile reserve in patients with myocardial hibernation remains to be determined. Ultimately, whether the alterations observed in adrenergic receptor density in myocardial hibernation are reversible after revascularization and account in part for the recovery of resting function would be difficult to answer clinically and would await confirmation in an experimental model.…”

Section: Adrenergic Receptors and Contractile Functionmentioning

confidence: 99%

Altered Adrenergic Receptor Density in Myocardial Hibernation in Humans

et al. 2000

View full text Add to dashboard Cite

Background-Alterations in adrenergic receptor densities can potentially contribute to myocardial dysfunction. Their relevance to myocardial hibernation in humans is unknown. Methods and Results-Accordingly, 22 transmural myocardial biopsies were obtained in 11 patients with ischemic ventricular dysfunction during bypass surgery, guided by transesophageal echocardiography. Patients underwent dobutamine echocardiography (DE) and rest scintigraphic studies before revascularization and DE at 3 to 4 months. ␣-and ␤-receptor density (ARD and BRD) and extent of fibrosis were quantified from the myocardial biopsies. Of the 22 segments, 16 had abnormal rest function and 6 were normal. Severely hypokinetic or akinetic segments showed a 2.4-fold increase in ARD with a concomitant 50% decrease in BRD compared with normal segments. An increase in ARD, a decrease in BRD to a lesser extent, and thus an increase in ARD/BRD ratio were seen in dysfunctional segments with contractile reserve compared with normal segments and were most pronounced in those without contractile reserve (PϽ0.001). Similar findings were observed if recovery of function or scintigraphic uptake was analyzed as a marker for viability. No significant relation between either ARD or BRD and percent myocardial fibrosis was noted (rϭ0.37 and Ϫ0.39, respectively). Conclusions-Thus, graded and reciprocal changes in ␣-and ␤-adrenergic receptor densities occur in viable, hibernating myocardium and may account in part for the observed depression in resting myocardial function and preserved contractile reserve in this entity.

show abstract

“…Coronary vasoconstriction in β -adrenoceptor-blocked hearts can be elicited by injection of phenylephrine and other α -adrenergic agonists. During conditions such as hypotension [85,[101][102][103] and myocardial ischemia [85,98,104] , in which myocardial oxygen delivery is impaired, adrenergic constriction competes with vasodilation produced by local metabolic mechanisms. They found that at the same level of myocardial oxygen consumption, blood flow was significantly higher in the presence of α -adrenergic blockade.…”

Section: Sympathetic Controlmentioning

confidence: 99%

“…They found that at the same level of myocardial oxygen consumption, blood flow was significantly higher in the presence of α -adrenergic blockade. Similarly, coronary blood flow increases during hypotension following α-adrenergic [101][102][103] . Studies in exercising animals have shown that α -adrenergic constriction restricts coronary blood flow during exercise [92,93,94,95,99,100] .…”

Section: Sympathetic Controlmentioning

confidence: 99%