Whole-body heating decreases pulmonary capillary wedge pressure and cerebral vascular conductance and causes an inotropic shift in the Frank-Starling curve. Whole-body cooling increases pulmonary capillary wedge pressure and cerebral vascular conductance without changing systolic function. These and other data indicate that factors affecting cardiac function may mechanistically contribute to syncope during heat stress and improvements in orthostatic tolerance during cold stress.
Changes in cardiac function may contribute to heat- and cold-induced alterations in orthostatic tolerance in humans.
1Institute for Neuromusculoskeletal Research, Ohio University; 2Departments of Biomedical Sciences and of Specialty Medicine, Ohio University College of Osteopathic Medicine, Athens, OH; 3Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas; and 4Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX
Address for correspondence: Thad E. Wilson, Ph.D., Ohio University-COM, 228 Irvine Hall, Athens, OH 45701 (E-mail: firstname.lastname@example.org).
Accepted for publication: September 20, 2010.
Associate Editor: Scott J. Montain, Ph.D., FACSM