Key result
Alpha- and beta 2-adrenergic receptor blockade significantly altered coronary blood flow velocity and late diastolic coronary resistance during exercise, demonstrating equal influence.
Alpha- and beta 2-adrenergic receptors exert equal but opposing influences on coronary resistance during exercise, with beta 2-receptors becoming more dominant after exercise training and sympathetic denervation.
Answers are grounded in this paper and cite their sources.
Provides mechanistic insight into coronary vasoregulation during exercise in animals; leaves open applicability to human physiology or therapy.
The effects of regional alpha- and specific beta 2-adrenergic receptor blockade on measurements of late diastolic coronary resistance (LDCR) and mean coronary blood flow velocity (CBFV) during exercise were examined in 14 conscious adult mongrel dogs. Specific beta 2-adrenergic receptor blockade (ICI 118.551) significantly decreased CBFV and increased LDCR by blockade of beta 2-vasodilator tone independent of alpha-adrenergic receptor-mediated tone and independent of altering myocardial metabolism. alpha-Adrenergic receptor blockade (phentolamine, 1 mg) significantly increased CBFV and decreased LDCR by blocking sympathetically mediated vasoconstrictor tone. There was no significant difference in the magnitude of response between alpha- and beta 2-adrenergic receptor blockade. These results demonstrate that alpha- and beta 2-adrenergic receptors have a significant and evidently equal influence on CBFV and LDCR during exercise. Four weeks of daily exercise and left stellate ganglionectomy (LSGx) prevented phentolamine-induced vasodilation but not ICI 118.551-induced vasoconstriction. This suggests that daily exercise and LSGx significantly decreased the alpha-adrenergic receptor-mediated vasoconstrictor tone on the coronary circulation, resulting in an apparently greater role for the coronary vascular beta 2-adrenergic receptor on the control of CBFV and LDCR during exercise.
No takes yet. Share an insight, caveat, or question.
DiCarlo et al. (1988) studied this question. Regional alpha- and specific beta 2-adrenergic receptor blockade (phentolamine and ICI 118.551) was evaluated on Late diastolic coronary resistance (LDCR) and mean coronary blood flow velocity (CBFV) during exercise. Alpha- and beta 2-adrenergic receptor blockade significantly altered coronary blood flow velocity and late diastolic coronary resistance during exercise, demonstrating equal influence.
Synapse has enriched 10 related papers. Consider them for comparative context: