Epicks: Andean highlanders, chronic mountain sickness and the regulation of resting blood pressure скачать в хорошем качестве

Epicks: Andean highlanders, chronic mountain sickness and the regulation of resting blood pressure

In this video, Lydia Simpson discusses her latest paper discussing Andean highlanders and chronic mountain sickness. Read more in Experimental Physiology Global REACH 2018: Andean highlanders, chronic mountain sickness and the integrative regulation of resting blood pressure. Lydia L. Simpson, Connor A. Howe, Samuel J. Oliver, Michael M. Tymko, Victoria L. Meah, Tony G.Dawkins, Gilberto Moralez, Andrew R. Steele, Christopher Gasho, Stephen A. Busch, Justin S. Lawley, Gustavo A. Vizcardo-Galindo, Rómulo J. Figueroa-Mujíca, Francisco C. Villafuerte , Phillip N. Ainslie, Mike Stembridge, Craig D. Steinback, Jonathan Moore https://physoc.onlinelibrary.wiley.co... Transcript: Hi, my name is Lydia Simpson, and I’m going to be discussing our recent paper published in the Extreme Environmental Physiology special issue of Experimental Physiology. Most highland native populations show excellent adaptation to the high altitude environment, due to their generational exposure to ambient hypoxia. However, a small proportion of these individuals, between 10–15%, cannot adapt to ambient hypoxia and develop the maladaptation syndrome Chronic Mountain Sickness (CMS). CMS is most prevalent in individuals native to the South American Andes and is a condition characterised by excessive erythrocytosis and exaggerated arterial hypoxemia for the resident altitude. Importantly, CMS is also associated with an increased risk of cardiovascular disease, including the development of hypertension. However, it was previously unclear as to whether altered autonomic regulation of blood pressure was apparent in those with CMS. Therefore, during the 2018 Global REACH expedition to the Cerro de Pasco region of Peru, we assessed integrative control of resting blood pressure in seven healthy Andean highlanders and eight Andean highlanders with mild CMS. We assessed total blood volume, sympathetic vasomotor activity (via microneurography) and also assessed arterial baroreflex function using the modified Oxford test. As expected, those with CMS had lower arterial oxygen saturation compared to healthy highlanders. They also had higher haemoglobin concentrations, higher haematocrits and a larger red blood cell volume, and this resulted in a larger total blood volume and a higher blood viscosity. Despite this, cardiac output, total peripheral resistance, and therefore mean arterial pressure, were similar between groups. In fact, the higher total blood volume and blood viscosity in CMS was balanced by a lower heart rate and lower sympathetic vasomotor activity. Furthermore, the sympathetic responsiveness to acute fluctuations in blood pressure (i.e. the sympathetic baroreflex gain) was similar between groups. Also the heart rate responsiveness to acute fluctuations in blood pressure (i.e. cardiovagal baroreflex gain) was actually augmented in those with CMS. Therefore, autonomic control of blood pressure was well preserved in individuals with CMS, and does not appear to contribute to the increased risk of cardiovascular disease reported in this population. A lower heart rate and sympathetic vasomotor activity appear to be a compensatory response to excessive erythrocytosis and an increase in red blood cell volume and allow normal resting arterial pressure to be maintained.