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Introduction: Visualization of the intact microvascular network in skeletal muscle requires labeling the entire network in whole mount preparations where muscle fibre length can be set to near optimal but the tools to do this are not clear., Methods: We intravascularly injected CD-1 mice with different fluorescently labelled lectins (fluorescent isolectin GS-IB4 (ISO), wheat germ agglutinin (WGA), lycopersicon esculentum (tomato) (LYCO) or FITC-labelled gel. Soleus, extensor digitorum longus, diaphragm, gluteus maximus and cremaster muscles were excised, pinned at optimal sarcomere length and viewed using fluorescence microscopy., Results: WGA and LYCO were the effective at labeling the entire vascular network with WGA labeling capillaries more bright. ISO labelled the arteriolar vasculature and early segments of the capillaries but not the full length of the capillaries or the venular network. FITC-labelled gel was effective at labelling the microvascular network but not all small vessels were consistently labelled. The pattern of staining for each labelling method was similar across all muscle fibre-types tested., Conclusions: WGA was optimal for perfusion labeling and visualization of the intact microvascular network in whole mount skeletal muscle preparations and can be used in combination with ISO to distinguish the arteriolar and venous sides of the network., (The Author(s). Published by S. Karger AG, Basel.)

Objective: We hypothesized that CO 2 and H + stimulate capillaries and arterioles to produce local and conducted vasodilations required to coordinate the distribution of blood flow to contracting skeletal muscle fibers., Methods: CO 2 and H + independently and in combination were applied to 2A arterioles (first branch order from the 1A feed arteriole) and capillaries of the in situ, blood-perfused hamster cremaster muscle. The resulting local and conducted vasodilations were measured., Results: H + (pH: 7.2-6.6) and CO 2 (5% and 10%) applied to the vascular network induced 2A arteriolar vasodilations, while 15% CO 2 produced vasoconstriction. Localized application of H + produced 2A arteriolar vasodilation, while 15% CO 2 resulted in a variable response. Simultaneous application of CO 2 and H + did not result in the predicted additive effects. Application of CO 2 and H + alone or combined on arterioles or capillaries did not induce a conducted response., Conclusions: CO 2 and H + produce arteriolar vasodilation but, critically, cannot stimulate the spread of vasodilation throughout the network, thus limiting their ability to coordinating blood flow to contracting skeletal muscle fibers. Given their potential for interaction, the importance of CO 2 and H + may lie in their ability to modify the effects of other vasodilators., (© 2018 John Wiley & Sons Ltd.)