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– When Lacy M. Alexander, PhD, began her career as a kinesiology researcher, she focused on the skin as a model of circulation for examining mechanisms of vascular function and dysfunction in diseases, as well as the influence of drug interventions.

“The skin is an accessible circulation; we see many of the same neural and endothelial pathways mediating vasodilation that we see throughout the entire vascular system,” Dr. Alexander, professor of kinesiology at Penn State University’s College of Health and Human Development, University Park, Pa., said during a lecture at the annual meeting of the American College for Sports Medicine.

Doug Brunk/MDedge News
Dr. Lacy M. Alexander

The main technique that she and other researchers use to examine microvascular endothelial function is intradermal microdialysis, which involves the placement of a thin catheter into the dermis. “This catheter has the ability to perfuse or infuse various substances into a bidirectional membrane,” Dr. Alexander explained. “This enables us to recover various substances into that catheter. We pair this with a measurement of skin blood flow with Doppler probes as well as the ability to control local temperature to either isolate reflex control of the human cutaneous circulation or elicit local changes in temperature to elicit vasodilation and vasoconstriction.”

In a 2005 article on evaluating the microcirculation in vascular disease, microvascular dysfunction is described as “a systemic disease process that occurs in a similar fashion in multiple tissue beds throughout the body”. Therefore, early identification of the mechanism leading to microvascular dysfunction is important, Dr. Alexander said. “We can also monitor the progression of disease and the progression of a given treatment if we have a noninvasive way to do that.”

A question that clinicians often ask Dr. Alexander is, do changes in forearm skin blood flow represent changes in, say, leg skin blood flow, or blood flow in other parts of the body? “The answer to that question is yes; we see similar changes in forearm skin that we see in other regions of the body,” she said. “We tend to use the forearm skin because there’s less UV damage, especially when we’re looking at questions related to human aging.”

Over the years, she and other investigators have used intradermal microdialysis to develop and refine many skin-specific approaches for examining endothelial function, including reactive hyperemia, direct drug delivery, local heating, whole body heating, local cooling, whole body cooling, and spectral analysis. For example, using this approach in the direct drug delivery realm, researchers have discovered that oral atorvastatin therapy restores cutaneous microvascular function by decreasing arginase activity in hypercholesterolemic middle-aged adults.

In more recent work using intradermal microdialysis, researchers have observed that peripheral microvascular function is impaired in adults with hypertension (Hypertension. 2017; 69[5]:902-9).



Another study using intradermal microdialysis found that 16 weeks of a sulfhydryl intervention improved endothelial function through nitric oxide and hydrogen sulfide-dependent mechanisms in adults with hypertension.

The technology has also helped to further understanding of nontraditional risk factors of microvascular dysfunction. In one study, researchers found that endothelium-dependent vasodilation is blunted in adults with major depressive disorder due to a reduced functional contribution of nitric oxide.

According to Dr. Alexander, a study being reviewed for publication found that microvascular endothelial function is impaired in women with endometriosis.

Also in 2019, a European Academy of Allergy and Clinical Immunology (EAACI) position paper on the use of intradermal microdialysis in investigations of the pathogenesis of chronic inflammatory skin diseases was published.

The broad focus of Dr. Alexander’s current projects includes examining the roles of arginase in nitric oxide synthase uncoupling in human vasculature with hypercholesterolemia and hypertension; inflammation-induced alteration in vasodilatory signaling with essential hypertension; the role of reactive oxygen species in altering vasoconstriction and vascular remodeling with hypertension, and the effects of common platelet inhibitors on microvascular function in human skin as they relate to basic mechanisms of skin blood flow and functional thermoregulatory outcomes. “The hope is that we can intervene with things like dietary and exercise interventions early on to mitigate this progression to avert cardiovascular disease,” she said.

Dr. Alexander disclosed that she has received research support from the National Heart, Lung, and Blood Institute, the National Dairy Council, the American College of Sports Medicine, and the American Heart Association.

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– When Lacy M. Alexander, PhD, began her career as a kinesiology researcher, she focused on the skin as a model of circulation for examining mechanisms of vascular function and dysfunction in diseases, as well as the influence of drug interventions.

“The skin is an accessible circulation; we see many of the same neural and endothelial pathways mediating vasodilation that we see throughout the entire vascular system,” Dr. Alexander, professor of kinesiology at Penn State University’s College of Health and Human Development, University Park, Pa., said during a lecture at the annual meeting of the American College for Sports Medicine.

Doug Brunk/MDedge News
Dr. Lacy M. Alexander

The main technique that she and other researchers use to examine microvascular endothelial function is intradermal microdialysis, which involves the placement of a thin catheter into the dermis. “This catheter has the ability to perfuse or infuse various substances into a bidirectional membrane,” Dr. Alexander explained. “This enables us to recover various substances into that catheter. We pair this with a measurement of skin blood flow with Doppler probes as well as the ability to control local temperature to either isolate reflex control of the human cutaneous circulation or elicit local changes in temperature to elicit vasodilation and vasoconstriction.”

In a 2005 article on evaluating the microcirculation in vascular disease, microvascular dysfunction is described as “a systemic disease process that occurs in a similar fashion in multiple tissue beds throughout the body”. Therefore, early identification of the mechanism leading to microvascular dysfunction is important, Dr. Alexander said. “We can also monitor the progression of disease and the progression of a given treatment if we have a noninvasive way to do that.”

A question that clinicians often ask Dr. Alexander is, do changes in forearm skin blood flow represent changes in, say, leg skin blood flow, or blood flow in other parts of the body? “The answer to that question is yes; we see similar changes in forearm skin that we see in other regions of the body,” she said. “We tend to use the forearm skin because there’s less UV damage, especially when we’re looking at questions related to human aging.”

Over the years, she and other investigators have used intradermal microdialysis to develop and refine many skin-specific approaches for examining endothelial function, including reactive hyperemia, direct drug delivery, local heating, whole body heating, local cooling, whole body cooling, and spectral analysis. For example, using this approach in the direct drug delivery realm, researchers have discovered that oral atorvastatin therapy restores cutaneous microvascular function by decreasing arginase activity in hypercholesterolemic middle-aged adults.

In more recent work using intradermal microdialysis, researchers have observed that peripheral microvascular function is impaired in adults with hypertension (Hypertension. 2017; 69[5]:902-9).



Another study using intradermal microdialysis found that 16 weeks of a sulfhydryl intervention improved endothelial function through nitric oxide and hydrogen sulfide-dependent mechanisms in adults with hypertension.

The technology has also helped to further understanding of nontraditional risk factors of microvascular dysfunction. In one study, researchers found that endothelium-dependent vasodilation is blunted in adults with major depressive disorder due to a reduced functional contribution of nitric oxide.

According to Dr. Alexander, a study being reviewed for publication found that microvascular endothelial function is impaired in women with endometriosis.

Also in 2019, a European Academy of Allergy and Clinical Immunology (EAACI) position paper on the use of intradermal microdialysis in investigations of the pathogenesis of chronic inflammatory skin diseases was published.

The broad focus of Dr. Alexander’s current projects includes examining the roles of arginase in nitric oxide synthase uncoupling in human vasculature with hypercholesterolemia and hypertension; inflammation-induced alteration in vasodilatory signaling with essential hypertension; the role of reactive oxygen species in altering vasoconstriction and vascular remodeling with hypertension, and the effects of common platelet inhibitors on microvascular function in human skin as they relate to basic mechanisms of skin blood flow and functional thermoregulatory outcomes. “The hope is that we can intervene with things like dietary and exercise interventions early on to mitigate this progression to avert cardiovascular disease,” she said.

Dr. Alexander disclosed that she has received research support from the National Heart, Lung, and Blood Institute, the National Dairy Council, the American College of Sports Medicine, and the American Heart Association.

– When Lacy M. Alexander, PhD, began her career as a kinesiology researcher, she focused on the skin as a model of circulation for examining mechanisms of vascular function and dysfunction in diseases, as well as the influence of drug interventions.

“The skin is an accessible circulation; we see many of the same neural and endothelial pathways mediating vasodilation that we see throughout the entire vascular system,” Dr. Alexander, professor of kinesiology at Penn State University’s College of Health and Human Development, University Park, Pa., said during a lecture at the annual meeting of the American College for Sports Medicine.

Doug Brunk/MDedge News
Dr. Lacy M. Alexander

The main technique that she and other researchers use to examine microvascular endothelial function is intradermal microdialysis, which involves the placement of a thin catheter into the dermis. “This catheter has the ability to perfuse or infuse various substances into a bidirectional membrane,” Dr. Alexander explained. “This enables us to recover various substances into that catheter. We pair this with a measurement of skin blood flow with Doppler probes as well as the ability to control local temperature to either isolate reflex control of the human cutaneous circulation or elicit local changes in temperature to elicit vasodilation and vasoconstriction.”

In a 2005 article on evaluating the microcirculation in vascular disease, microvascular dysfunction is described as “a systemic disease process that occurs in a similar fashion in multiple tissue beds throughout the body”. Therefore, early identification of the mechanism leading to microvascular dysfunction is important, Dr. Alexander said. “We can also monitor the progression of disease and the progression of a given treatment if we have a noninvasive way to do that.”

A question that clinicians often ask Dr. Alexander is, do changes in forearm skin blood flow represent changes in, say, leg skin blood flow, or blood flow in other parts of the body? “The answer to that question is yes; we see similar changes in forearm skin that we see in other regions of the body,” she said. “We tend to use the forearm skin because there’s less UV damage, especially when we’re looking at questions related to human aging.”

Over the years, she and other investigators have used intradermal microdialysis to develop and refine many skin-specific approaches for examining endothelial function, including reactive hyperemia, direct drug delivery, local heating, whole body heating, local cooling, whole body cooling, and spectral analysis. For example, using this approach in the direct drug delivery realm, researchers have discovered that oral atorvastatin therapy restores cutaneous microvascular function by decreasing arginase activity in hypercholesterolemic middle-aged adults.

In more recent work using intradermal microdialysis, researchers have observed that peripheral microvascular function is impaired in adults with hypertension (Hypertension. 2017; 69[5]:902-9).



Another study using intradermal microdialysis found that 16 weeks of a sulfhydryl intervention improved endothelial function through nitric oxide and hydrogen sulfide-dependent mechanisms in adults with hypertension.

The technology has also helped to further understanding of nontraditional risk factors of microvascular dysfunction. In one study, researchers found that endothelium-dependent vasodilation is blunted in adults with major depressive disorder due to a reduced functional contribution of nitric oxide.

According to Dr. Alexander, a study being reviewed for publication found that microvascular endothelial function is impaired in women with endometriosis.

Also in 2019, a European Academy of Allergy and Clinical Immunology (EAACI) position paper on the use of intradermal microdialysis in investigations of the pathogenesis of chronic inflammatory skin diseases was published.

The broad focus of Dr. Alexander’s current projects includes examining the roles of arginase in nitric oxide synthase uncoupling in human vasculature with hypercholesterolemia and hypertension; inflammation-induced alteration in vasodilatory signaling with essential hypertension; the role of reactive oxygen species in altering vasoconstriction and vascular remodeling with hypertension, and the effects of common platelet inhibitors on microvascular function in human skin as they relate to basic mechanisms of skin blood flow and functional thermoregulatory outcomes. “The hope is that we can intervene with things like dietary and exercise interventions early on to mitigate this progression to avert cardiovascular disease,” she said.

Dr. Alexander disclosed that she has received research support from the National Heart, Lung, and Blood Institute, the National Dairy Council, the American College of Sports Medicine, and the American Heart Association.

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