Contribution of perfusion pressure to vascular resistance response during head-up tilt

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 281; no. 1; pp. H371 - H375
• Main Authors: Imadojemu, Virginia A, Lott, Mary E. J, Gleeson, Kevin, Hogeman, Cynthia S, Ray, Chester A, Sinoway, Lawrence I
• Format: Journal Article
• Language: English
• Published: Legacy CDMS 01.07.2001
• Subjects: Adult; Arm - blood supply; Arm - innervation; Blood Flow Velocity - physiology; Blood Pressure - physiology; Female; Heart Rate - physiology; Humans; Leg - blood supply; Leg - innervation; Life Sciences (General); Male; Median Nerve - physiology; Middle Aged; Muscle, Skeletal - innervation; Peroneal Nerve - physiology; Space life sciences; Sympathetic Nervous System - physiology; Tilt-Table Test; Vascular Resistance - physiology; Non-Nasa Center; Nasa Discipline Cardiopulmonary; NASA Discipline Cardiopulmonary; Non-NASA Center
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.2001.281.1.h371

1  Division of Pulmonary, Allergy, and Critical Care and 2  Division of Cardiology, The Milton S. Hershey Medical Center, The Pennsylvania State University College of Medicine, Hershey, 17033; and 3  Lebanon Veterans Affairs Medical Center, Lebanon, Pennsylvania 17042 We measured brachial and femoral artery flow velocity in eight subjects and peroneal and median muscle sympathetic nerve activity (MSNA) in five subjects during tilt testing to 40°. Tilt caused similar increases in MSNA in the peroneal and median nerves. Tilt caused a fall in femoral artery flow velocity, whereas no changes in flow velocity were seen in the brachial artery. Moreover, with tilt, the increase in the vascular resistance employed (blood pressure/flow velocity) was greater and more sustained in the leg than in the arm. The ratio of the percent increase in vascular resistance in leg to arm was 2.5:1. We suggest that the greater vascular resistance effects in the leg were due to an interaction between sympathetic nerve activity and the myogenic response. sympathetic nervous system; blood pressure regulation