Protocol for non-invasive pulsed-Doppler evaluation of blood flow in the mouse ophthalmic artery.

The number of reliable and non-invasive techniques to characterize ocular blood flow is limited. Here, we present a protocol for identifying a soft tissue window in the orbital aperture using pulsed-Doppler ultrasonography to offer real-time, non-invasive blood flow velocity monitoring in the mouse ophthalmic artery. We describe steps for preparing a mouse, positioning the ultrasound probe, and acquiring and recording signals.

Non-invasive real-time pulsed Doppler assessment of blood flow in mouse ophthalmic artery.

Non-invasive and high-temporal resolution methods for characterizing blood flow in mouse cranial arteries, such as the ophthalmic artery (OphA), are lacking. We present an application of pulsed Doppler ultrasound to provide real-time, non-invasive measurement of blood flow velocity in the OphA through an identified soft tissue window in the mouse head. We confirmed the identity of the artery and mapped its origin from the internal carotid artery by a combination of microcomputed tomography (microCT) vascular imaging and transient occlusion of the internal carotid artery.

Methods to Utilize Pulse Wave Velocity to Measure Alterations in Cerebral and Cardiovascular Parameters.

Alzheimer's Disease (AD) is a global health issue, affecting over 6 million in the United States, with that number expected to increase as the aging population grows. As a neurodegenerative disorder that affects memory and cognitive functions, it is well established that AD is associated with cardiovascular risk factors beyond only cerebral decline. However, the study of cerebrovascular techniques for AD is still evolving.

Update on the Use of Pulse Wave Velocity to Measure Age-Related Vascular Changes.

Purpose Of Review: Pulse wave velocity (PWV) is an important and well-established measure of arterial stiffness that is strongly associated with aging. Age-related alterations in the elastic properties and integrity of arterial walls can lead to cardiovascular disease. PWV measurements play an important role in the early detection of these changes, as well as other cardiovascular disease risk factors, such as hypertension.

3D reconstruction of murine mitochondria reveals changes in structure during aging linked to the MICOS complex.

During aging, muscle gradually undergoes sarcopenia, the loss of function associated with loss of mass, strength, endurance, and oxidative capacity. However, the 3D structural alterations of mitochondria associated with aging in skeletal muscle and cardiac tissues are not well described. Although mitochondrial aging is associated with decreased mitochondrial capacity, the genes responsible for the morphological changes in mitochondria during aging are poorly characterized.

Three-dimensional mitochondria reconstructions of murine cardiac muscle changes in size across aging.

With sparse treatment options, cardiac disease remains a significant cause of death among humans. As a person ages, mitochondria breakdown and the heart becomes less efficient. Heart failure is linked to many mitochondria-associated processes, including endoplasmic reticulum stress, mitochondrial bioenergetics, insulin signaling, autophagy, and oxidative stress.

Characterization of atrial and ventricular remodeling in an improved minimally invasive mouse model of transverse aortic constriction.

Introduction: Heart failure (HF) is the leading cause of death worldwide. Most large and small animal disease models of HF are based on surgical procedures. A common surgical technique to induce HF is transverse aortic constriction (TAC), which induces pressure overload.

Cardiovascular hemodynamics in mice with tumor necrosis factor receptor-associated factor 2 mediated cytoprotection in the heart.

Introduction: Many studies in mice have demonstrated that cardiac-specific innate immune signaling pathways can be reprogrammed to modulate inflammation in response to myocardial injury and improve outcomes. While the echocardiography standard parameters of left ventricular (LV) ejection fraction, fractional shortening, end-diastolic diameter, and others are used to assess cardiac function, their dependency on loading conditions somewhat limits their utility in completely reflecting the contractile function and global cardiovascular efficiency of the heart. A true measure of global cardiovascular efficiency should include the interaction between the ventricle and the aorta (ventricular-vascular coupling, VVC) as well as measures of aortic impedance and pulse wave velocity.

Sex-specific phenotypes in the aging mouse heart and consequences for chronic fibrosis.

The incidence of diastolic dysfunction increases with age in both humans and mice. This is characterized by increased passive stiffness and slower relaxation of the left ventricle. The stiffness arises at least partially from progressively increased interstitial collagen deposition because of highly secretory fibroblasts.

Aortic acceleration as a noninvasive index of left ventricular contractility in the mouse.

The maximum value of the first derivative of the invasively measured left ventricular (LV) pressure (+ dP/dt or P') is often used to quantify LV contractility, which in mice is limited to a single terminal study. Thus, determination of P' in mouse longitudinal/serial studies requires a group of mice at each desired time point resulting in "pseudo" serial measurements. Alternatively, a noninvasive surrogate for P' will allow for repeated measurements on the same group of mice, thereby minimizing physiological variability and requiring fewer animals.

Topoisomerase 2B Decrease Results in Diastolic Dysfunction p53 and Akt: A Novel Pathway.

Diastolic dysfunction is condition of a stiff ventricle and a function of aging. It causes significant cardiovascular mortality and morbidity, and in fact, three million Americans are currently suffering from this condition. To date, all the pharmacological clinical trials have been negative.

Argininosuccinate Lyase Deficiency Causes an Endothelial-Dependent Form of Hypertension.

Primary hypertension is a major risk factor for ischemic heart disease, stroke, and chronic kidney disease. Insights obtained from the study of rare Mendelian forms of hypertension have been invaluable in elucidating the mechanisms causing primary hypertension and development of antihypertensive therapies. Endothelial cells play a key role in the regulation of blood pressure; however, a Mendelian form of hypertension that is primarily due to endothelial dysfunction has not yet been described.

Improved Cardiovascular Function in Old Mice After N-Acetyl Cysteine and Glycine Supplemented Diet: Inflammation and Mitochondrial Factors.

Metabolic, inflammatory, and functional changes occur in cardiovascular aging which may stem from oxidative stress and be remediable with antioxidants. Glutathione, an intracellular antioxidant, declines with aging, and supplementation with glutathione precursors, N-acetyl cysteine (NAC) and glycine (Gly), increases tissue glutathione. Thirty-month old mice were fed diets supplemented with NAC or NAC+Gly and, after 7 weeks, cardiac function and molecular studies were performed.

16-Channel Flexible System to Measure Electrophysiological Properties of Bioengineered Hearts.

As tissue engineering continues to mature, it is necessary to develop new technologies that bring insight into current paradigms and guide improvements for future experiments. To this end, we have developed a system to characterize our bioartificial heart model and compare them to functional native structures. In the present study, the hearts of adult Sprague-Dawley were decellularized resulting in a natural three-dimensional cardiac scaffold.

Noninvasive Measurement of EKG Properties of 3D Artificial Heart Muscle.

Developing and testing a custom fabricated 16-electrode noninvasive direct contact system was necessary to assess the electrical properties of bioengineered heart muscle and to further evaluate the efficacy of cardiac constructs. By culturing neonatal rat primary cardiac cells on a fibrin gel, we constructed 3D artificial heart muscle (3D-AHM), as described in previous studies, which were used in validating this novel system. Electrical and mechanical functional assessment of the tissues was performed, which yielded contractile forces of the tissues, electrical field potential characteristics, and tissue conduction velocities (CV) (20-170 cm/s).

SRC-1 Regulates Blood Pressure and Aortic Stiffness in Female Mice.

Framingham Heart Study suggests that dysfunction of steroid receptor coactivator-1 may be involved in the development of hypertension. However, there is no functional evidence linking steroid receptor coactivator-1 to the regulation of blood pressure. We used immunohistochemistry to map the expression of steroid receptor coactivator-1 protein in mouse brain, especially in regions implicated in the regulation of blood pressure.

Defective Association of the Platelet Glycoprotein Ib-IX Complex with the Glycosphingolipid-Enriched Membrane Domain Inhibits Murine Thrombus and Atheroma Formation.

Localization of the platelet glycoprotein Ib-IX complex to the membrane lipid domain is essential for platelet adhesion to von Willebrand factor and subsequent platelet activation in vitro. Yet, the in vivo importance of this localization has never been addressed. We recently found that the disulfide linkage between Ibα and Ibβ is critical for the association of Ibα with the glycosphingolipid-enriched membrane domain; in this study, we established a transgenic mouse model expressing this mutant human Ibα that is also devoid of endogenous Ibα (HαSSMα(-/-)).

Left Atrial Volume and Pulmonary Artery Diameter Are Noninvasive Measures of Age-Related Diastolic Dysfunction in Mice.

Impaired cardiac diastolic function occurs with aging in many species and may be difficult to measure noninvasively. In humans, left atrial (LA) volume is a robust measure of chronic diastolic function as the LA is exposed to increased left ventricular filling pressures. We hypothesized that LA volume would be a useful indicator of diastolic function in aging mice.

32-Channel System to Measure the Electrophysiological Properties of Bioengineered Cardiac Muscle.

The purpose of this study was to develop, assess, and validate a custom 32-channel system to analyze the electrical properties of 3-D artificial heart muscle (3D-AHM). In this study, neonatal rat cardiac cells were cultured in a fibrin gel to drive the formation of 3D-AHM. Once the tissues were fully formed, the customized electrocardiogram (EKG) sensing system was used to obtain the different electrophysiological characteristics of the muscle constructs.

And the beat goes on: maintained cardiovascular function during aging in the longest-lived rodent, the naked mole-rat.

The naked mole-rat (NMR) is the longest-lived rodent known, with a maximum lifespan potential (MLSP) of >31 years. Despite such extreme longevity, these animals display attenuation of many age-associated diseases and functional changes until the last quartile of their MLSP. We questioned if such abilities would extend to cardiovascular function and structure in this species.

microRNA-22 promotes heart failure through coordinate suppression of PPAR/ERR-nuclear hormone receptor transcription.

Increasing evidence suggests that microRNAs are intimately involved in the pathophysiology of heart failure. MicroRNA-22 (miR-22) is a muscle-enriched miRNA required for optimum cardiac gene transcription and adaptation to hemodynamic stress by pressure overload in mice. Recent evidence also suggests that miR-22 induces hypertrophic growth and it is oftentimes upregulated in end stage heart failure.

A new rodent model for obstructive sleep apnea: effects on ATP-mediated dilations in cerebral arteries.

Obstructive sleep apnea (OSA), a condition in which the upper airway collapses during sleep, is strongly associated with metabolic and cardiovascular diseases. Little is known how OSA affects the cerebral circulation. The goals of this study were 1) to develop a rat model of chronic OSA that involved apnea and 2) to test the hypothesis that 4 wk of apneas during the sleep cycle alters endothelium-mediated dilations in middle cerebral arteries (MCAs).

Systematic characterization of myocardial inflammation, repair, and remodeling in a mouse model of reperfused myocardial infarction.

Mouse models of myocardial infarction are essential tools for the study of cardiac injury, repair, and remodeling. Our current investigation establishes a systematic approach for quantitative evaluation of the inflammatory and reparative response, cardiac function, and geometry in a mouse model of reperfused myocardial infarction. Reperfused mouse infarcts exhibited marked induction of inflammatory cytokines that peaked after 6 hr of reperfusion.