Project Abstract |
Exposure to microgravity causes cardiovascular deconditioning. As a consequence, microgravity-adapted astronauts returning to the gravity of Earth can experience both orthostatic intolerance and decreased exercise capacity in a very similar manner to people on earth with spontaneous orthostatic hypotension or those on long term bedrest. A model of simulated microgravity in the rat indicates that this may be due to decreased contractility of arterial smooth muscle. Here, we report that this decreased contractility can be reversed with mechanical removal of the endothelium in the thoracic aorta and lead to an even greater contraction than in control tissues. This difference may be due to an increased sensitivity to muscarinic agonists such as methylfurmethide which in turn may be due to an increased sensitivity to nitric oxide. Further, we report on an increased contractility deficit in Sprague-Dawley rats exposed to simulated microgravity as compared to Wistars. |
