Project Title

Innervation of Blood Vessels in the Human Heart

Authors' Affiliations

1 Jocelyn Gilbert, 1 Chloe Garbe, 1 Tasha Nelson, 1 Elizabeth Smith, 2 Peter Hanna, 2 Kalyanam Shivkumar, 3 Igor Efimov, and 1 Donald Hoover,1 Department of Biomedical Sciences, 1 ETSU, Johnson City, TN, 2 UCLA, Los Angeles, CA, 3 GWU, Washington, DC.

Location

Culp Ballroom

Start Date

4-7-2022 9:00 AM

End Date

4-7-2022 12:00 PM

Poster Number

112

Faculty Sponsor’s Department

Biomedical Sciences

Name of Project's Faculty Sponsor

Donald Hoover

Classification of First Author

Undergraduate Student

Competition Type

Competitive

Type

Poster Presentation

Project's Category

Anatomy, Morphology, Neuroscience, Physiology

Abstract or Artist's Statement

Coronary arteries bring nutrient-rich oxygenated blood to the heart muscle. They are regulated primarily by metabolic factors released in times of increased oxygen demand. These factors cause vasodilation, thereby increasing regional blood flow. Coronary arteries can also be regulated by neural input from sympathetic (noradrenergic) nerves and parasympathetic (cholinergic) nerves. However, very little is known about the neurophysiology or innervation of coronary arteries, especially in humans. Therefore, the purpose of this study is to determine the regional presence and abundance of cholinergic and noradrenergic nerves in human coronaries. To evaluate the presence, abundance, and distribution of these nerves in particular regions of the normal heart, we obtained samples from a donor heart that was rejected for transplant. Heart samples were collected at George Washington University or UCLA, fixed in paraformaldehyde, and cryoprotected. De-identified samples were shipped to ETSU for sectioning (30 um), and immunostaining. Noradrenergic nerves were stained using an antibody specific to tyrosine hydroxylase (TH) and cholinergic nerves were stained with an antibody specific to vesicular ACh transporter (VAChT). The stained sections were viewed and photographed at either 4X or 10X magnification using Olympus BX41 microscope with an Olympus DP74 digital camera. Nerve densities were rated at low, moderate, high, or absent. The abundance of noradrenergic or cholinergic nerves varied for different regions of the heart. The right atrial appendage had a high abundance of both nerve types around vessels. The right ventricular outflow tract had high nerve abundance for noradrenergic nerves around vessels and moderate to low abundance for cholinergic nerves around vessels. The left atrial appendage presented a low abundance of both nerve types around all sizes of vessels and surrounding tissue. The mid left ventricular (LV) freewall lateral presented moderate abundance for adrenergic nerves around vessels and surrounding tissue, but cholinergic nerves were low abundance around vessels and surrounding tissue. The basal LV had moderate to high abundance for noradrenergic nerves around the vessels and surrounding tissue (containing high abundance in nerve bundles). For cholinergic nerves, the basal LV had moderate abundance of nerves in surrounding tissue, high nerve abundance for small vessels, and moderate abundance for larger vessels. The LV apex had moderate abundance of noradrenergic nerves around vessels and no cholinergic nerves around vessels. These findings suggest that both cholinergic and noradrenergic nerves could have varied influence on coronary blood flow. Noradrenergic nerves become more dominant from the base to the apex of the heart. Cholinergic innervation becomes less prominent from the base to the apex. Therefore, cholinergic nerves likely have less influence on coronary blood flow when compared to that of noradrenergic nerves.

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Apr 7th, 9:00 AM Apr 7th, 12:00 PM

Innervation of Blood Vessels in the Human Heart

Culp Ballroom

Coronary arteries bring nutrient-rich oxygenated blood to the heart muscle. They are regulated primarily by metabolic factors released in times of increased oxygen demand. These factors cause vasodilation, thereby increasing regional blood flow. Coronary arteries can also be regulated by neural input from sympathetic (noradrenergic) nerves and parasympathetic (cholinergic) nerves. However, very little is known about the neurophysiology or innervation of coronary arteries, especially in humans. Therefore, the purpose of this study is to determine the regional presence and abundance of cholinergic and noradrenergic nerves in human coronaries. To evaluate the presence, abundance, and distribution of these nerves in particular regions of the normal heart, we obtained samples from a donor heart that was rejected for transplant. Heart samples were collected at George Washington University or UCLA, fixed in paraformaldehyde, and cryoprotected. De-identified samples were shipped to ETSU for sectioning (30 um), and immunostaining. Noradrenergic nerves were stained using an antibody specific to tyrosine hydroxylase (TH) and cholinergic nerves were stained with an antibody specific to vesicular ACh transporter (VAChT). The stained sections were viewed and photographed at either 4X or 10X magnification using Olympus BX41 microscope with an Olympus DP74 digital camera. Nerve densities were rated at low, moderate, high, or absent. The abundance of noradrenergic or cholinergic nerves varied for different regions of the heart. The right atrial appendage had a high abundance of both nerve types around vessels. The right ventricular outflow tract had high nerve abundance for noradrenergic nerves around vessels and moderate to low abundance for cholinergic nerves around vessels. The left atrial appendage presented a low abundance of both nerve types around all sizes of vessels and surrounding tissue. The mid left ventricular (LV) freewall lateral presented moderate abundance for adrenergic nerves around vessels and surrounding tissue, but cholinergic nerves were low abundance around vessels and surrounding tissue. The basal LV had moderate to high abundance for noradrenergic nerves around the vessels and surrounding tissue (containing high abundance in nerve bundles). For cholinergic nerves, the basal LV had moderate abundance of nerves in surrounding tissue, high nerve abundance for small vessels, and moderate abundance for larger vessels. The LV apex had moderate abundance of noradrenergic nerves around vessels and no cholinergic nerves around vessels. These findings suggest that both cholinergic and noradrenergic nerves could have varied influence on coronary blood flow. Noradrenergic nerves become more dominant from the base to the apex of the heart. Cholinergic innervation becomes less prominent from the base to the apex. Therefore, cholinergic nerves likely have less influence on coronary blood flow when compared to that of noradrenergic nerves.