Interactions of vasoactive substances in exercise hyperemia: O2, K+, and osmolality

Ns, Skinner; Jc, Costin

doi:10.1152/ajplegacy.1970.219.5.1386

Cited by 21 publications

(13 citation statements)

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“…Skinner and Powell (30) have shown that potassium ions and decreased P02 have an additive effect in the production of decreased vascular resistance. It now appears that there is a similar relationship between elevated osmolarity and lowered Po 2 (31). The biphasic responses at low constant-flow perfusion in the current study support the idea that two or more agents participate iji the control of vascular resistance.…”

Section: Mohrman Cant Sparkssupporting

confidence: 82%

Time Course of Vascular Resistance and Venous Oxygen Changes following Brief Tetanus of Dog Skeletal Muscle

Mohrman

Cant

Sparks

1973

Circulation Research

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The time courses of vascular resistance and venous blood oxygen (O 2 ) saturation following a brief tetanus of isolated dog calf muscle were studied during free-flow (constant-pressure), high constant-flow (>30 ml/100 g min-1 ), and low constant-flow (<24 ml/100 g mirr 1 ) perfusion. A monophasic decrease in resistance followed a 1-second tetanus during either free-flow or high constant-flow perfusion. The transient decrease in vascular resistance during high constant-flow perfusion returned to control before the return of the decrease in end-capillary oxygen tension. Thus, it seems unlikely that the vascular response to a brief tetanus during free-flow or high constant-flow perfusion was controlled by a factor related to oxidative metabolism. A biphasic resistance response followed a brief tetanus during low constant-flow perfusion. This vascular response had a longer duration than the response during free-flow or high constant-flow perfusion. It returned to control with approximately the same time course as that for tissue O 2 consumption and could therefore be controlled by factors related to oxidative metabolism. These findings support the hypothesis that exercise hyperemia is due to multiple factors. Moreover, they indicate that, under the conditions of free-flow perfusion or high constant-flow perfusion, the vascular response to a brief tetanus is not solely controlled by factors directly associated with tissue oxidative metabolism. KEY WORDS flow washoutexercise hyperemia constant-flow perfusion metabolic vasodilator blood flow constant-pressure perfusion• Several factors contributing to exercise hyperemia have been identified (1-3), and most of these factors have been implicated as metabolic vasodilators on the basis of two criteria: (1) steady-state exercise produces changes in the venous level of the substance which correlate with changes in the vascular resistance and (2) the substance produces vasodilation when it is infused into the arterial supply of resting skeletal muscle. However, such experiments are difficult to interpret, because steady-state exercise produces many alterations in the chemical composition of the venous effluent of

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Section: Mohrman Cant Sparkssupporting

confidence: 82%

Time Course of Vascular Resistance and Venous Oxygen Changes following Brief Tetanus of Dog Skeletal Muscle

Mohrman

Cant

Sparks

1973

Circulation Research

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“…Classic studies of functional vasodilation in response to contractile activity had focused on the regulation of tissue oxygen pressure (pO 2 ) [2, 3] and the ability of “vasodilator substances” produced by active skeletal muscle fibers to relax vascular smooth muscle cells (SMCs) [12, 13]. In practice, functional vasodilation entails the ability to override (i.e., “escape”) sympathetic vasoconstriction [10, 11, 14] through mechanisms that – remarkably – are still being resolved.…”

Section: Background and Perspectivementioning

confidence: 99%

Integration and Modulation of Intercellular Signaling Underlying Blood Flow Control

Segal¹

2015

J Vasc Res

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Vascular resistance networks control tissue blood flow in concert with regulating arterial perfusion pressure. In response to increased metabolic demand, vasodilation arising in arteriolar networks ascends to encompass proximal feed arteries. By reducing resistance upstream, ascending vasodilation (AVD) increases blood flow into the microcirculation. Once initiated, e.g. through local activation of K⁺ channels in endothelial cells (ECs), hyperpolarization is conducted through gap junctions along the endothelium. Via EC projections through the internal elastic lamina, hyperpolarization spreads into the surrounding smooth-muscle cells (SMCs) through myoendothelial gap junctions (MEGJs) to promote their relaxation. Intercellular signaling through electrical signal transmission (i.e. cell-to-cell conduction) can thereby coordinate vasodilation along and among the branches of microvascular resistance networks. Perivascular sympathetic nerve fibers course through the adventitia and release norepinephrine to stimulate SMCs via α-adrenoreceptors to produce contraction. In turn, SMCs can signal ECs through MEGJs to activate K⁺ channels and attenuate sympathetic vasoconstriction. Activation of K⁺ channels along the endothelium will dissipate electrical signal transmission and inhibit AVD, thereby restricting blood flow into the microcirculation while maintaining peripheral resistance and perfusion pressure. This review explores the origins and nature of the intercellular signaling that governs blood flow control in skeletal muscle with respect to the interplay between AVD and sympathetic innervation. Whereas these interactions are integral to daily activity and athletic performance, determining the interplay between respective signaling events provides insight into how selective interventions can improve tissue perfusion and oxygen delivery during vascular disease.

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“…Oxygen has been reported to alter the response of the peripheral vasculature to potassium (19,20,26). Since the solution Po 2 was rather arbitrarily set at low levels, the effect of potassium at higher solution Po 2 levels was also investigated.…”

Section: 8 Dulingmentioning

confidence: 99%

“…Many investigators have shown that potassium at the increased concentrations observed in venous blood during exercise and hypoxia can relax smooth muscle both in vivo (5)(6)(7)(8)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and in vitro (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31). Therefore, this ion.…”

mentioning

confidence: 99%

Effects of potassium ion on the microcirculation of the hamster.

Duling¹

1975

Circulation Research

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The vasoactive properties of potassium were assessed in the microcirculation of the hamster cremaster muscle and the muscular and epithelial portions of the hamster cheek pouch. Tissues were transilluminated and suffused with a physiological salt solution whose potassium concentration varied from 0 to 20 mM. Vessel diameters were measured and normalized as a percent of the control diameter (± SE) observed during exposure to 4.7 mM K + . Altering the potassium concentration in the suffusion solution caused a transient vascular response. The peak changes in the vascular diameter of the arterioles supplying striated muscle varied directly with the suffusion solution potassium concentration from a minimum of 78 ± 3% in 0 mM K + to 155 ± 15% in 15 mM K". Vascular diameter increases were sustained for the full 5-minute test period only in 15 mM K+. In the epithelial portions of the cheek pouch, only the constrictor component of the potassium response was observed. The data indicate that potassium is sufficiently potent to participate in initiating functional hyperemia in striated muscle and might cause as much as a 6.3-fold increase in flow. Functional hyperemias exceeding approximately 3 minutes cannot be due to potassium ion, since the dilation induced by this agent is transient.• Cells contain a large store of labile potassium that can be released by various stimuli such as muscle contraction and hypoxia (1-9). Many investigators have shown that potassium at the increased concentrations observed in venous blood during exercise and hypoxia can relax smooth muscle both in vivo (5)(6)(7)(8)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and in vitro (21-31). Therefore, this ion. may be important in the local control of blood flow. However, further quantification of the reactivity of resistance vessels to the ion must be carried out before accurate estimates of the importance of potassium in blood flow regulation can be made. These data can be obtained by studying microvessel responses to alterations in suffusion solution potassium concentrations, but such experiments have only been performed on pial vessels (11,16,17). Furthermore, no data are currently available showing the temporal response pattern of microvessels during variations in potassium concentration. These data are of particular interest in view of the transient potassium ion release during functional hyperemia in striated muscle (7,8) and the transient vascular smooth muscle response to potassium both in vitro (26-32) and in vivo (10). A preliminary report of this work was presented at the Fall Meeting of the American Physiological Society, August, 1974. This work was done during Dr. Duling's tenure as an Established Investigator of the American Heart Association.Received September 20, 1974. Accepted for publication June 4, 1975. I have therefore studied the responses of the arterioles of the hamster cremaster muscle and cheek pouch to changes in the potassium concentration of a superfusion solution. The aims of the experiment were to: (1) estab...

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Interactions of vasoactive substances in exercise hyperemia: O2, K+, and osmolality

Cited by 21 publications

References 0 publications

Time Course of Vascular Resistance and Venous Oxygen Changes following Brief Tetanus of Dog Skeletal Muscle

Time Course of Vascular Resistance and Venous Oxygen Changes following Brief Tetanus of Dog Skeletal Muscle

Integration and Modulation of Intercellular Signaling Underlying Blood Flow Control

Effects of potassium ion on the microcirculation of the hamster.

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