Key result
α-adrenergic stimulation elicits greater vascular sensitivity in fast versus slow skeletal muscle.
Why the study?
Differences in vascular properties between fast and slow skeletal muscles in response to α-adrenergic stimulation were investigated due to their known biochemical and biophysical differences.
Demonstrates physiological differences in vascular reactivity and resting blood flow patterns between fast and slow skeletal muscles.
May guide studies of sympathetic muscle perfusion control; leaves open human translation and clinical relevance.
In the light of known differences in bio-chemical, histological, and biophysical characteristics of fast and slow muscle, it was thought feasible to investigate possible differences in vascular properties. The present study has shown that vascular reactivity to α-adrenergic stimulation by both topical application of catecholamines (epinephrine and norepinephrine) and reflex activation of sympathetic nerves, is graded in both fast and slow muscles from precapillary sphincters which are the most sensitive, to small and then larger arterioles. In addition, the vessels of fast muscle are more sensitive to stimulation by those agents than are the vessels of slow muscle. The vascular bed in fast muscle is characterized by vasomotion (intermittency of flow rate and pattern) and many momentarily inactive capillaries (no moving red cells) in the resting state, whereas the flow in slow muscle capillaries is much more steady and uniform.
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Sarah D. Gray (2008) studied this question. α-adrenergic stimulation (topical catecholamines and sympathetic nerve activation) vs. Fast vs slow skeletal muscle was evaluated on Vascular reactivity. Vessels of fast skeletal muscle are more sensitive to α-adrenergic stimulation than vessels of slow muscle, with reactivity graded from precapillary sphincters to larger arterioles.
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