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This article describes a simple and inexpensive "shock and awe" classroom demonstration for understanding the importance of carbon dioxide (CO[subscript 2]) in acid-base regulation. Before class, a solution was prepared by adding sodium bicarbonate and universal indicator solution to a sample of distilled water contained in a standard plastic water bottle. Upon arriving to class, the students observed the blue-violet solution and were told that the solution could be considered a surrogate for the arterial blood. At this point, a small piece of solid CO[subscript 2] (dry ice) was dropped into the bottle and a balloon, filled with confetti, was placed over the opening of the bottle. As expected, the solution rapidly turned bright pink/red as the solid CO[subscript 2] underwent sublimation and filled the balloon. At this point the balloon was "popped", making a loud noise and flying confetti about the room contributing to the "shock and awe" appeal. Furthermore, CO[subscript 2] was released simulating ventilation. To simulate hyperventilation, a piece of tubing connected to a hand bicycle pump was inserted into the bottle and air was pumped into the solution. As expected, the solution slowly changed from red to orange to yellow to green and finally approached blue as CO[subscript 2] was forced out of the solution. This straightforward and easy to perform demonstration provoked intense interest and provided a memorable learning experience by attracting and sustaining attention and increasing students' motivation to focus on the material.

Pulse oximetry has become the standard of care in operating rooms, intensive care units, and hospitals worldwide. A pulse oximeter continuously and noninvasively monitors the functional oxygen saturation of hemoglobin in arterial blood (Sa[subscript O2]). Sa[subscript O2] is so important in medical care that it is often regarded as a fifth vital sign. Before pulse oximetry, arterial puncture for blood gas analysis was the only method available to determine Sa[subscript O2] and to identify the presence of hypoxemia. Pulse oximetry is based on the principle that oxygenated hemoglobin (O2Hb) absorbs more near-infrared light than deoxyhemoglobin (HHb) and HHb absorbs more red light than O[subscript 2]Hb. It is important to understand the principles of pulse oximetry, how the equipment works, and its limitations to interpret the information it provides. Accordingly, we used colored balloons to introduce the physics of how a pulse oximeter detects and measures oxyhemoglobin and deoxyhemoglobin in pulsatile (arterial) and nonpulsatile (venous and capillary) blood. The foundations of oximetry started in the 1700s with Johann Lambert (1728-1777). We approached this complex physics in a straightforward way while still providing an understanding of the fundamental concepts developed by Johann Lambert in 1760.

The movement of air into and out of the lungs is facilitated by changes in pressure within the thoracic cavity relative to atmospheric pressure, as well as the resistance encountered by airways. In this process, the movement of air into and out of the lungs is driven by pressure gradients established by changes in lung volume and intra-alveolar pressure. However, pressure never sucks! The concept that pressure never sucks, pressure only pushes encapsulates a fundamental principle in the behavior of gases. This concept challenges common misconceptions about pressure, shedding light on the dynamic forces that govern the movement of gases. In this Illumination, we explore the essence of this concept and its applications in pulmonary ventilation. Pressure is one of the most important concepts in physics and physiology. Atmospheric pressure at sea level is equal to 1 atmosphere or around 101,325 Pascal [Pa (1 Pa = 1 N/m2)]. This huge pressure is pushing down on everything all the time. However, this pressure is difficult to understand because we do not often observe the power of this incredible force. We used five readily available, simple, and inexpensive demonstrations to introduce the physics and power of pressure. This extraordinarily complex physics concept was approached in a straightforward and inexpensive manner while still providing an understanding of the fundamental concepts. These simple demonstrations introduced basic concepts and addressed common misconceptions about pressure. NEW & NOTEWORTHY: The concept that pressure never sucks, pressure only pushes challenges common misconceptions about pressure, shedding light on the dynamic forces that govern the movement of gases. In this Illumination, we will explore the essence of this concept and its applications in pulmonary ventilation. Specifically, we used five readily available, simple, inexpensive demonstrations to introduce the physics and power of pressure. [ABSTRACT FROM AUTHOR]

High salt intake is one of the major dietary determinants of hypertension and cardiovascular disease in Japan and throughout the world. Although dietary salt restriction may be of clinical benefit in salt-sensitive individuals, many individuals may not wish, or be able to, reduce their intake of salt. Thus, identification of functional foods that can help protect against mechanistic abnormalities mediating salt-induced hypertension is an issue of considerable medical and scientific interest. According to the "vasodysfunction" theory of salt-induced hypertension, the hemodynamic abnormality initiating salt-induced increases in blood pressure usually involves subnormal vasodilation and abnormally increased vascular resistance in response to increased salt intake. Because disturbances in nitric oxide activity can contribute to subnormal vasodilator responses to increased salt intake that often mediate blood pressure salt sensitivity, increased intake of functional foods that support nitric oxide activity may help to reduce the risk for salt-induced hypertension. Mounting evidence indicates that increased consumption of traditional Japanese vegetables and other vegetables with high nitrate content such as table beets and kale can promote the formation of nitric oxide through an endothelial independent pathway that involves reduction of dietary nitrate to nitrite and nitric oxide. In addition, recent studies in animal models have demonstrated that modest increases in nitrate intake can protect against the initiation of salt-induced hypertension. These observations are: (1) consistent with the view that increased intake of many traditional Japanese vegetables and other nitrate rich vegetables, and of functional foods derived from such vegetables, may help maintain healthy blood pressure despite a high salt diet; (2) support government recommendations to increase vegetable intake in the Japanese population.

The term "abnormal pressure natriuresis" refers to a subnormal effect of a given level of blood pressure (BP) on sodium excretion. It is widely believed that abnormal pressure natriuresis causes an initial increase in BP to be sustained. We refer to this view as the "pressure natriuresis theory of chronic hypertension." The proponents of the theory contend that all forms of chronic hypertension are sustained by abnormal pressure natriuresis, irrespective of how hypertension is initiated. This theory would appear to follow from "the three laws of long-term arterial pressure regulation" stated by Guyton and Coleman more than 3 decades ago. These "laws" articulate the concept that for a given level of salt intake, the relationship between arterial pressure and sodium excretion determines the chronic level of BP. Here, we review and examine the recent assertion by Beard that these "laws" of long-term BP control amount to nothing more than a series of tautologies. Our analysis supports Beard's assertion, and also indicates that contemporary investigators often use tautological reasoning in support of the pressure natriuresis theory of chronic hypertension. Although the theory itself is not a tautology, it does not appear to be testable because it holds that abnormal pressure natriuresis causes salt-induced hypertension to be sustained through abnormal increases in cardiac output that are too small to be detected.

The article discusses the negative consequences of misunderstanding race as a biological concept. It highlights that racial groups are not genetically discrete and that beliefs in biological differences between races can lead to racial bias and disparities in healthcare. The article also emphasizes that race is a social category with biological consequences, and calls for a rejection of genetic determinism and the elimination of institutional racism in medical education. The authors argue that correcting the misunderstanding of race as biology can help create a more inclusive and equitable healthcare system. [Extracted from the article]

It is widely held that in response to high salt diets, normal individuals are acutely and chronically resistant to salt-induced hypertension because they rapidly excrete salt and retain little of it so that their blood volume, and therefore blood pressure, does not increase. Conversely, it is also widely held that salt-sensitive individuals develop salt-induced hypertension because of an impaired renal capacity to excrete salt that causes greater salt retention and blood volume expansion than that which occurs in normal salt-resistant individuals. Here we review results of both acute and chronic salt-loading studies that have compared salt-induced changes in sodium retention and blood volume between normal subjects (salt-resistant normotensive control subjects) and salt-sensitive subjects. The results of properly controlled studies strongly support an alternative view: during acute or chronic increases in salt intake, normal salt-resistant subjects undergo substantial salt retention and do not excrete salt more rapidly, retain less sodium, or undergo lesser blood volume expansion than do salt-sensitive subjects. These observations: (i) directly conflict with the widely held view that renal excretion of sodium accounts for resistance to salt-induced hypertension, and (ii) have implications for contemporary understanding of how various genetic, immunologic, and other factors determine acute and chronic blood pressure responses to high salt diets.

This critical review directly challenges the prevailing theory that a transient increase in cardiac output caused by genetically mediated increases in activity of the ENaC in the aldosterone sensitive distal nephron, or of the NCC in the distal convoluted tubule, accounts entirely for the hemodynamic initiation of all Mendelian forms of salt-dependent hypertension (Figure 1). The prevailing theory of how genetic mutations enable salt to hemodynamically initiate Mendelian forms of salt-dependent hypertension in humans (Figure 1) depends on the results of salt-loading studies of cardiac output and systemic vascular resistance in nongenetic models of hypertension that lack appropriate normal controls. The theory is inconsistent with the results of studies that include measurements of the initial hemodynamic changes induced by salt loading in normal, salt-resistant controls. The present analysis, which takes into account the results of salt-loading studies that include the requisite normal controls, indicates that mutation-induced increases in the renal tubular activity of ENaC or NCC that lead to transient increases in cardiac output will generally not be sufficient to enable increases in salt intake to initiate the increased BP that characterizes Mendelian forms of salt-dependent hypertension (Table). The present analysis also raises questions about whether mutation-dependent increases in renal tubular activity of ENaC or NCC are even necessary to account for increased risk for salt-dependent hypertension in most patients with such mutations. We propose that for the genetic alterations underlying Mendelian forms of salt-dependent hypertension to enable increases in salt intake to initiate the increased BP, they must often cause vasodysfunction, ie, an inability to normally vasodilate and decrease systemic vascular resistance in response to increases in salt intake within dietary ranges typically observed in most modern societies. A subnormal ability to vasodilate in response to salt loading could be caused by mutation-related disturbances originating in the vasculature itself or in sites outside the vasculature (eg, brain or adrenal glands) that have the capacity to affect vascular function.

Students' attitudes towards teaching and learning must be addressed with the same seriousness and effort as we address content. Establishing a personal connection and addressing our students' basic psychological needs will produce positive attitudes towards teaching and learning and develop life-long learners. It will also promote constructive student-teacher relationships that have a profound influence on our students' approach towards school. To begin this process, consider the major tenets of the Self-Determination Theory. The Self-Determination Theory of human motivation focuses on our students' innate psychological needs and the degree to which an individual's behavior is self-motivated and self-determined. Faculty can satisfy the innate psychological needs by addressing our students' desire for relatedness, competence and autonomy. Relatedness refers to our students' need to feel connected to others, to be a member of a group, to have a sense of communion and to develop close relationships with others. Competence is believing our students can succeed, challenging them to do so and imparting that belief in them. Autonomy involves considering the perspectives of the student and providing relevant information and opportunities for student choice and initiating and regulating their own behaviors. Establishing a personal connection and addressing our students' basic psychological needs will improve our teaching, inspire and engage our students and promote positive attitudes towards teaching and learning while reducing competition and increasing compassion. These are important goals because unless students are inspired and motivated and have positive attitudes towards teaching and learning our efforts will fail to meet their full potential.

We hypothesized that the intellectual development of students, i.e., their beliefs about the nature of knowledge and learning, affects their intrinsic motivation and class performance. Specifically, we hypothesized that students with low intellectual development (i.e., the naive beliefs that knowledge is simple, absolute, and certain) have low intrinsic motivation and low class performance, whereas students with high intellectual development (i.e., more sophisticated beliefs that knowledge is complex, tentative, and evolving) have high intrinsic motivation and class performance. To test this hypothesis, we administered the Learning Context Questionnaire to measure intellectual development. In addition, we administered the Intrinsic Motivation Inventory to assess our students' intrinsic motivation. Furthermore, we performed regression analyses between intellectual development with both intrinsic motivation and class performance. The results document a positive relationship among intellectual development, intrinsic motivation, and class performance for female students only. In sharp contrast, there was a negative relationship between intellectual development, intrinsic motivation, and class performance for male students. The slope comparisons documented significant differences in the slopes relating intellectual development, intrinsic motivation, and class performance between female and male students. Thus, female students with more sophisticated beliefs that knowledge is personally constructed, complex, and evolving had higher intrinsic motivation and class performance. In contrast, male students with the naive beliefs that the structure of knowledge is simple, absolute, and certain had higher levels of intrinsic motivation and class performance. The results suggest that sex influences intellectual development, which has an effect on intrinsic motivation for learning a specific topic.

Students are naturally curious and inquisitive with powerful intrinsic motives to probe, learn, and understand their world. Accordingly, class activities must capitalize on this inherently energetic and curious nature so that learning becomes a lifelong activity where students take initiative for learning, are skilled in learning, and want to learn new things. This report describes a student-centered class activity, the "flipped exam," designed to achieve this goal. The flipped exam was a collaborative, group effort, and learning was interactive. It included a significant proportion (~30-35%) of material not covered in class. This required students to actively search for content and context, dynamically making connections between what they knew and what they learned, grappling with complexity, uncertainty, and ambiguity, and finally discovering answers to important questions. Accordingly, the need or desire to know was the catalyst for meaningful learning. Student assessment was determined by behavioral noncognitive parameters that were based on the observation of the student and the student's work as well as cognitive parameters (i.e., the student's score on the examination). It is our view that the flipped exam provided a student-centered activity in which students discovered, because of the need to know and opportunities for discussion, the important concepts and principles we wanted them to learn.

Our students are naturally curious, with powerful intrinsic motives to understand their world. Accordingly, we, as teachers, must capitalize on this inherently active and curious nature so that learning becomes a lifelong activity where students take initiative for learning, are skilled in learning, and want to learn new things. Achieving this goal requires an understanding of student attitudes, beliefs, characteristics, and motivations. To achieve this goal, we administered the intrinsic motivation inventory (IMI) to assess our students' interest and enjoyment, perceived choice, and perceived competence while taking our undergraduate exercise physiology class (46 students; 20 female students and 26 male students). The interest and enjoyment subscale is considered the self-reported measure of intrinsic motivation. The perceived choice and perceived competence concepts are theorized to be positive predictors of both self-reported and behavioral measures of intrinsic motivation. Our results documented a significant increase in course grade with an increase in survey score for the interest and enjoyment subscale of the IMI when female and male students were combined. Specifically, each increase in survey score for the interest and enjoyment subscale of the IMI was associated with a significant ("P" less than 0.05) increase of 3.9% in course grade. However, the increase in survey score was associated with a significantly greater ("P" less than 0.05) increase in course grade for male (6.1%) compared with female (0.3%) students. These results have implications for both classroom practice and educational reform policies.

Teachers often overrate the importance of their content and underrate their influence. However, students forget much of the content that they memorize. Thus, attempts to teach students all that they will need to know is futile. Rather, it is important that students develop an interest and love for lifelong learning. Inspiring and motivating students is critical because unless students are inspired and motivated our efforts are pointless. Once students are inspired and motivated, there are countless resources available to learn more about a subject. Thus, teachers must abandon the mistaken notion that unless they "cover the content" students will be unprepared for the future and they will have failed as teachers. Teachers must not worry about "losing" or "wasting" valuable lecture time for in-class discussion, collaborative problem-solving, and inquiry-based activities that take time away from covering content. Rather than worrying about covering content, teachers must design activities to focus student learning on how to use scientific knowledge to solve important questions. This is important because learning is not committing a set of facts to memory but the ability to use resources to find, evaluate, and use information. In fact, memorizing anything discourages deep thinking. Deep thinking is essential because understanding is the residue of thinking! To encourage thinking we must create a joy, an excitement, and a love for learning. We must make learning fun; because if we are successful, our students will be impatient to run home, study, and contemplate-to really learn.

We used collaborative testing in a veterinary physiology course (65 students) to answer the following questions: 1) do students with individual correct responses or students with individual incorrect responses change their answers during group testing? and 2) do high-performing students make the decisions, that is, are low-performing students carried by high-performing peers? To address these questions, students first completed the exam in the traditional format as individuals. After completing the exam as individuals, students completed the same exam in groups of two. Finally, the same questions were discussed by the instructor and students (instructor feedback). We found that students with individual incorrect responses changed their answers during group testing more often than students with individual correct responses (odds ratio: 7.58, P less than 0.01). Furthermore, student feedback was more beneficial when group members had different individual answers than when they had same individual answers (P less than 0.05). In addition, when group members had different individual answers, more answers were changed to correct responses than to incorrect responses (77% vs. 23%, P less than 0.01). It was more important to have the correct answer than to be the high-performing student, because the student with the correct response (being either the high- or low-performing student) generally prevailed ([approximately] 80% of the time, P = 0.5). Finally, the positive effects of group testing (77% of total effects, P less than 0.05) were due to students who changed their individual answer to the correct response after discussion with peers with the correct response and also with the incorrect individual response. (Contains 1 table and 4 figures.)

We used collaborative group testing in a veterinary physiology course (65 students) to test the hypothesis that all students (e.g., high-performing and low-performing students of each group) benefit from collaborative group testing. In this format, students answered questions in the traditional format as individuals. Immediately after completing the exam as individuals, students answered the same questions in groups of two, and, finally, the same questions were discussed by the instructor and students. We measured two learning outcomes for every student: individual and group test scores. Based on individual test scores, students were categorized as "high performing" (students with higher individual scores) or "low performing" (students with lower individual scores). Finally, student evaluations of the format were collected. Collaborative group testing enhanced student performance. Specifically, group scores were higher than individual scores (P less than 0.001). Importantly, the size of the collaborative testing effect was large for the population and for the low-performing students; however, the collaborative testing effect was small for the high-performing students. Finally, student evaluations of this testing format were very positive. In conclusion, collaborative group testing was beneficial for all students; however, collaborative testing was significantly more beneficial for low-performing students. (Contains 5 tables and 1 figure.)

When teaching and learning about alveolar ventilation with our class of 300 first-year medical students, we use four simple, inexpensive "models." The models, which encourage research-oriented learning and help our students to understand complex ideas, are distributed to the students before class. The students anticipate something new every day, and the models provide elements of surprise and physical examples and are designed to help students to understand 1) cohesive forces of the intrapleural space, 2) chest wall and lung dynamics, 3) alveolar volumes, and 4) regional differences in ventilation. Students are drawn into discussion by the power of learning that is associated with manipulating and thinking about objects. Specifically, the models encourage thinking about complex interactions, and the students appreciate manipulating objects and actually understanding how they work. Using models also allows us to show students how we think as well as what we know. Finally, students enjoy taking the models home to demonstrate to friends and family "how the body works" as well as use the models as future study aids. (Contains 6 figures.)

Students have specific learning style preferences, and these preferences may be different between male and female students. Understanding a student's learning style preference is an important consideration when designing classroom instruction. Therefore, we administered the visual, auditory, reading/writing, kinesthetic (VARK) learning preferences questionnaire to our first-year medical students; 38.8% (97 of 250 students) of the students returned the completed questionnaire. Both male (56.1%) and female (56.7%) students preferred multiple modes of information presentation, and the numbers and types of modality combinations were not significantly different between genders. Although not significantly different, the female student population tended to be more diverse than the male population, encompassing a broader range of sensory modality combinations within their preference profiles. Instructors need to be cognizant of these differences and broaden their range of presentation styles accordingly. (Contains 3 figures. The VARK Questionnaire is appended.)

The curriculum is packed with so much content that teachers resort to telling students what they know and students simply commit facts to memory. The packed curriculum leaves little time for students to acquire a deep understanding of the subject or to develop life-long skills such as critical thinking, problem solving, and communication. However, learning is not committing a set of facts to memory, but the ability to use resources to find, evaluate, and apply information. This paper addresses these concerns by discussing "how we learn" and reviewing the literature on what works to improve learning. It is clear that active processing of information, not passive reception of information, leads to learning. That is, students must construct their own understanding of concepts, relationships, and procedures. Teachers can encourage this process by carefully considering the type and organization of information as well as instructional strategies. Specifically, teachers should reduce the total amount of factual information students are expected to memorize, reduce our use of the passive lecture format, and devote much more effort to helping students become active, independent learners and problem solvers. Collaborative learning activities, interactive models, educational games, and establishing a culture of inquiry/scholarship are critical for achieving these goals.

We tested the hypothesis that peer instruction enhances student performance on qualitative problem-solving questions. To test this hypothesis, qualitative problems were included in a peer instruction format during our Physiology course. Each class of 90 min was divided into four to six short segments of 15 to 20 min each. Each short segment was followed by a qualitative problem-solving scenario that could be answered with a multiple-choice quiz. All students were allowed 1 min to think and to record their answers. Subsequently, students were allowed 1 min to discuss their answers with classmates. Students were then allowed to change their first answer if desired, and both answers were recorded. Finally, the instructor and students discussed the answer. Peer instruction significantly improved student performance on qualitative problem-solving questions (59.3 plus or minus 0.5% vs. 80.3 plus or minus 0.4%). Furthermore, after peer instruction, only 6.5% of the students changed their correct response to an incorrect response; however, 56.8% of students changed their incorrect response to a correct response. Therefore, students with incorrect responses changed their answers more often than students with correct responses. In conclusion, pausing four to six times during a 90-min class to allow peer instruction enhanced student performance on qualitative problem-solving questions.

Students must be able to interpret, relate, and incorporate new information with existing knowledge and apply the new information to solve novel problems. Peer instruction is a cooperative learning technique that promotes critical thinking, problem solving, and decision-making skills. Therefore, we tested the hypothesis that peer instruction enhances meaningful learning or transfer, defined as the student's ability to solve novel problems or the ability to extend what has been learned in one context to new contexts. To test this hypothesis, our undergraduate exercise physiology class of 38 students was randomly divided into two groups: group A (n = 19) and group B (n = 19). A randomized crossover design in which students either answered questions individually or during peer instruction was used to control for time and order effects. The first factor that influences meaningful learning is the degree of mastery of the original material. Importantly, peer instruction significantly enhanced mastery of the original material. Furthermore, the student's ability to solve novel problems was significantly enhanced following peer instruction. Thus pausing two to three times during a 50-min class to allow peer instruction enhanced the mastery of the original material and enhanced meaningful learning, i.e., the student's ability to solve novel problems.

Spirometers are useful for enhancing students' understanding of normal lung volumes, capacities, and flow rates. Spirometers are also excellent for understanding how lung diseases alter ventilation volumes. However, spirometers are expensive, complex, and not appropriate for programs with limited space and budgets. Therefore, we developed a simple, inexpensive, small model of a spirometer. Activity-based models are more valuable for enhancing learning than many hours of passive instruction. The model spirometer enables students to measure ventilation volumes as well as simulate lung diseases and positive pressure (mechanical) ventilation. The spirometer consists of a glass 5-ml syringe connected to the "tracheal tube" of an existing model [(1), Fig. 1]. A glass syringe is used because the plunger slides with less resistance. The spirometer must be filled with air before it is attached to the tracheal tube. When the plunger of the lung apparatus ("diaphragm") is pulled down, the air contained in the spirometer flows into the balloon ("lung"). Conversely, when the diaphragm is pushed up, the air flows from the lung into the spirometer. This volume, "tidal volume," can be measured. In addition, the number of "breaths" per time, "respiratory rate," can be determined, and minute ventilation can be calculated by multiplying tidal volume by respiratory rate. By use of this approach, students are able to determine lung volumes, capacities, and flow rates. Furthermore, the effects of obstructive and restrictive lung diseases can be simulated. An obstructive lung disease can be simulated by placing a clamp on the tracheal tube. A restrictive lung disease can be simulated by limiting the range of the diaphragm movement. Finally, mechanical ventilation can be simulated by using the plunger of the spirometer, forcing air to move into and out of the lung. This simple addition to an existing model (1) enhances students? understanding of ventilation volumes.

This article discusses the rise in depression and anxiety levels among students and the compassionate policies that some educators are implementing to address these issues. These policies include test retakes, flexible deadlines, recorded lectures, and mental health breaks. The article argues that while these policies may seem helpful, they may actually hinder student success and personal growth. It suggests that students should be encouraged to actively engage with academic stressors and develop coping skills, rather than avoiding them. The article questions whether these compassionate policies truly promote mental health, academic achievement, and resilience. [Extracted from the article]

When the spinal cord is injured at or below thoracic level 5 (T5), cardiovascular control is markedly unbalanced as the heart and blood vessels innervated by upper thoracic segments remain under brain stem control, whereas the vasculature of the lower body is affected by unregulated spinal reflexes. Importantly, the regulation of heart rate and cardiac function is abnormal after spinal cord injury (SCI) at T5 because sympathetic outflow to the heart is increased. An increase in tonic sympathetic outflow may be attributable to multiple mechanisms, such as increases in cardiac sympathetic innervation density, altered morphology of stellate ganglia neurons, and/or structural neuroplasticity of cardiac sympathetic preganglionic neurons (SPNs). Furthermore, these neuroplastic changes associated with SCI may be mediated by nerve growth factor (NGF). NGF is a neurotrophin that supports the survival and differentiation of sympathetic neurons and enhances target innervation. Therefore, we tested the hypothesis that T5 spinal cord transection (T5X) is associated with an increased left ventricular (LV) NGF content, LV sympathetic innervation density, and cardiac SPN arborization. In intact and paraplegic (9 wk posttransection) rats, LV NGF content (ELISA), LV sympathetic innervation density (tyrosine hydroxylase-immunohistoehemistry), and cardiac SPN arborization (cholera toxin B immunohistochemistry and Sholl Analysis) were determined. Paraplegia, compared with intact, significantly increased LV NGF content, LV sympathetic innervation density, and cardiac SPN arborization. Thus, altered autonomic behavior following SCI is associated with structural neuroplastic modifications. cardiovascular risks; arrhythmia doi: 10.1152/ajpregu.00329.2010.

Individuals with spinal cord injuries above thoracic level 6 (T6) experience episodic bouts of life-threatening hypertension as part of a condition termed autonomic dysreflexia. The paroxysmal hypertension can be caused by a painful stimulus below the level of the injury. Targeted ablation of mesenteric projecting sympathetic neurons may reduce the severity of autonomic dysreflexia by reducing sympathetic activity. Therefore, cholera toxin B subunit (CTB) conjugated to saporin (SAP; a ribosomal inactivating protein that binds to and inactivates ribosomes) was injected into the celiac ganglion to test the hypothesis that targeted ablation of mesenteric projecting sympathetic neurons reduces the pressor response to pain in conscious, spinal cord-transected rats. Nine Sprague-Dawley male rats underwent a spinal cord transection between thoracic vertebrae 4 and 5. Following recovery (5 wk), all rats were instrumented with a radio telemetry device for recording arterial pressure and bilateral catheters in the gluteus maximus muscles for the infusion of hypertonic saline (h[Na.sup.+][Cl.sup.-]). Subsequently, the hemodynamic responses to intramuscular injection of h[Na.sup.+][Cl.sup.-] (100 [micro]1 and 250 [micro]l, in random order) were determined. Following the experiments in the no celiac ganglia injected condition (NGI), rats received injections of CTB-SAP (n = 5) or CTB (n = 3) into the celiac ganglia. CTB-SAP rats, compared with NGI and CTB rats, had reduced pressor responses to h[Na.sup.+][Cl.sup.-]. Furthermore, the number of stained neurons in the celiac ganglia and spinal cord (segments [T.sub.6]-[T.sub.12]), was reduced in CTB-SAP rats. Thus, CTB-SAP retrogradely transported from the celiac ganglia is effective at ablating mesenteric projecting sympathetic neurons and reducing the pressor response to pain in spinal cord-transected rats. autonomic dysreflexia; spinal cord injury; sympathectomy doi: 10.1152/ajpregu.00755.2009.

The Cardiac Arrhythmia Suppression Trial demonstrated that antiarrhythmic drugs not only fail to prevent sudden cardiac death, but actually increase overall mortality. These findings have been confirmed in additional trials. The 'proarrhythmic' effects of most currently available antiarrhythmic drugs makes it essential that we investigate novel strategies for the prevention of sudden cardiac death. Targeted ablation of cardiac sympathetic neurons may become a therapeutic option by reducing sympathetic activity. Thus cholera toxin B subunit (CTB) conjugated to saporin (a ribosomal inactivating protein that binds to and inactivates ribosomes; CTB-SAP) was injected into both stellate ganglia to test the hypothesis that targeted ablation of cardiac sympathetic neurons reduces the susceptibility to ischemia-induced, sustained ventricular tachycardia in conscious rats. Rats were randomly divided into three groups: 1) control (no injection); 2) bilateral stellate ganglia injection of CTB; and 3) bilateral stellate ganglia injection of CTB-SAP. CTB-SAP rats had a reduced susceptibility to ischemiainduced, sustained ventricular tachycardia. Associated with the reduced susceptibility to ventricular arrhythmias were a reduced number of stained neurons in the stellate ganglia and spinal cord (segments [T.sub.1]-T4), as well as a reduced left ventricular norepinephrine content and sympathetic innervation density. Thus CTB-SAP retrogradely transported from the stellate ganglia is effective at ablating cardiac sympathetic neurons and reducing the susceptibility to ventricular arrhythmias. cholera toxin B subunit; stellate ganglion; neurotoxin; saporin; sympathectomy doi: 10.1152/ajpheart.00955.2009.