Increased sensitivity of end-organ responses to neuroendocrine stimuli as a result of prolonged exposure to the relative inactivity of microgravity has recently been hypothesized. This notion is based on the inverse relationship between circulating norepinephrine and beta-adrenoreceptor sensitivity. Beta-adrenoreceptor activity is reduced in individuals who have elevated plasma norepinephrine as as a result of regular exposure to upright posture and physical exercise. In contrast, adrenoreceptor hypersensitivity has been reported in patients with dysautonomias in which circulating catecholamines are absent or reduced. Taken together, these studies and the observation that circulating plasma norepinephrine has been reduced during spaceflight and in groundbased simulations of microgravity prompt the suggestion that adrenoreceptor hypersensitivity may be a consequence of the adaptation to spaceflight. We conducted an experiment designed to measure cardiovascular responses to adrenoreceptor agonists in human subjects before and after prolonged exposure to 6 degrees head-down tilt (HDT) to test the hypothesis that adaptation to microgravity increases adrenoreceptor responsiveness, and that this adaptation is associated with reduced levels of circulating norepinephrine.

Download full-text PDF

Source

Publication Analysis

Top Keywords

prolonged exposure
8
circulating norepinephrine
8
plasma norepinephrine
8
adrenoreceptor hypersensitivity
8
increased beta-adrenergic
4
beta-adrenergic responsiveness
4
responsiveness induced
4
induced days
4
exposure
4
days exposure
4

Similar Publications

Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity globally. It is estimated that 17.9 million people died from CVDs in 2019, which represents 32 % of all deaths worldwide.

View Article and Find Full Text PDF

In 2012, a social issue arose concerning a high incidence of cholangiocarcinoma (bile duct cancer) among printing workers. The cause was prolonged exposure to high concentrations of 1,2-dichloropropane that was included in the ink cleaning agent. Until then, it was not known that this substance could cause cancer in humans.

View Article and Find Full Text PDF

Objective: This study investigated the long-term health risks associated with occupational noise exposure. By using 9 years of health examination data from a major manufacturing company in Taiwan, this study compared the health indices of employees in noise-intensive and non-noise-intensive work environments.

Methods: A retrospective analysis of 6278 health examination reports spanning 9 years was conducted to compare 20 health indices among 166 employees evenly distributed between noise-intensive and non-noise-intensive workgroups.

View Article and Find Full Text PDF

Background: With the aging of the population, the deterioration of visual and auditory functions amongst the elderly has attracted much attention. Age-related hearing loss (ARHL) and age-related macular degeneration (AMD) are common eye and ear diseases that seriously affect the quality of life of elderly population.

Methods: This study utilised a whole cohort sampling method, with a total of 713 participants aged 50 years and older in the community from June 2022 to October 2023, resulting in the inclusion of 620 participants.

View Article and Find Full Text PDF

We perceive and understand others' emotional states from multisensory information such as facial expressions and vocal cues. However, such cues are not always available or clear. Can partial loss of visual cues affect multisensory emotion perception? In addition, the COVID-19 pandemic has led to the widespread use of face masks, which can reduce some facial cues used in emotion perception.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!